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key gets all the traffic https://media.himanshukukreja.in/lectures/week-01-data-at-scale--day-04-hot-keys-and-skew/poster.jpg Why traffic follows power laws, how a hot key drags down its whole partition, how to spot one with a Count-Min Sketch, and the layered defence (edge, local cache, split keys, coalescing) that takes a skewed URL shortener's p99 from 500 ms to 20 ms. https://media.himanshukukreja.in/lectures/week-01-data-at-scale--day-04-hot-keys-and-skew/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-01-data-at-scale--day-05-session-store-design Session store design: 10 million users, every request https://media.himanshukukreja.in/lectures/week-01-data-at-scale--day-05-session-store-design/poster.jpg Designing a session store for 10 million concurrent users end to end: sticky vs distributed vs client-side sessions, sizing a Redis Cluster, local caching and invalidation, what users see when a datacentre fails, and the written decision between Redis, DynamoDB and a custom build. https://media.himanshukukreja.in/lectures/week-01-data-at-scale--day-05-session-store-design/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-01-data-at-scale--capstone-interview-week-1-url-shortner-at-scale Capstone: design a URL shortener at scale, in 45 minutes https://media.himanshukukreja.in/lectures/week-01-data-at-scale--capstone-interview-week-1-url-shortner-at-scale/poster.jpg A full mock interview for TinyLink: clarify, estimate 120,000 redirects a second and 300 TB, sketch the architecture, then deep-dive into short code generation, viral URLs, sharding, rate limits and replication, and finish with edge cases, failures and monitoring. Every Week 1 idea in one answer. https://media.himanshukukreja.in/lectures/week-01-data-at-scale--capstone-interview-week-1-url-shortner-at-scale/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-02-failure-first-design--week-02-preview Week 2 Preview: assume everything fails https://media.himanshukukreja.in/lectures/week-02-failure-first-design--week-02-preview/poster.jpg Week 2 assumes everything you built will fail: timeouts, retries, idempotency, circuit breakers, delivery guarantees and leader election, practised on a payment pipeline, a webhook delivery system and a distributed job scheduler. https://media.himanshukukreja.in/lectures/week-02-failure-first-design--week-02-preview/video.mp4 540 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-02-failure-first-design--day-01-timeout-hell Timeout Hell: how long do you wait? https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-01-timeout-hell/poster.jpg Why a slow service is worse than a dead one, why averages lie, and how to set timeouts for a payment service that calls fraud check, bank and notification: P99 times 2 to 3, a 4.5-second budget, deadline propagation, cascade failures and bulkheads, connection vs read timeouts, adaptive timeouts and hedged requests. https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-01-timeout-hell/video.mp4 1320 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-02-failure-first-design--day-02-idempotency-in-practice Idempotency: charged exactly once, however many clicks https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-02-idempotency-in-practice/poster.jpg Why a client can't tell a lost request from a lost response, and how idempotency keys make the Day 1 payment service safe to retry: the processing, completed and failed record, who makes the key, how long to keep it, checking the bank after a timeout, double clicks, crashes, partial completion, and defence in depth. https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-02-idempotency-in-practice/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-02-failure-first-design--day-03-circuit-breakers Circuit breakers: stop calling what's clearly broken https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-03-circuit-breakers/poster.jpg When the bank is clearly failing, stop calling it: the closed, open and half-open states, what counts as a failure, rate instead of count, fallbacks you can and can't fake, the thundering herd on recovery, servers that disagree, outages a breaker hides, and how breakers, retries and bulkheads stack with Day 1 timeouts and Day 2 idempotency. https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-03-circuit-breakers/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-02-failure-first-design--day-04-webhook-delivery Webhook delivery: at least once, to systems you don't control https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-04-webhook-delivery/poster.jpg Delivering a million webhooks an hour to receivers that are slow, down or lying: why at-least-once plus idempotent receivers is the only honest guarantee, the event bus, dispatcher, partitioned queues and workers, a 39-hour retry schedule, HMAC signatures and replay protection, sizing the workers, and getting a receiver that was down for 2 hours back in 13 minutes instead of 2 hours. https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-04-webhook-delivery/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-02-failure-first-design--day-05-distributed-cron Distributed cron: once, on schedule, while servers die https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-05-distributed-cron/poster.jpg Why a scheduled job runs three times on three servers, why locks with and without expiry both fail, and how leader election with leases, fencing tokens, heartbeats, stuck-job detection and idempotent, resumable jobs get you effectively-once execution. Then the leader dies mid-job, the real-world tools, and every Week 2 pattern inside one order-processing job. https://media.himanshukukreja.in/lectures/week-02-failure-first-design--day-05-distributed-cron/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-02-failure-first-design--capstone-interview-week-2-flash-sale-for-megamart Capstone: a global flash sale for MegaMart, in 45 minutes https://media.himanshukukreja.in/lectures/week-02-failure-first-design--capstone-interview-week-2-flash-sale-for-megamart/poster.jpg A full mock interview: 5 million users chasing 10,000 units in 10 minutes. Clarify, estimate 150,000 requests a second and 80,000 notifications a second, sketch the architecture, then deep-dive into atomic claims in Redis, a checkout that never double-charges, 2.4 million notifications in seconds, and a sale scheduler that starts each sale once. Every Week 1 and Week 2 idea in one answer. https://media.himanshukukreja.in/lectures/week-02-failure-first-design--capstone-interview-week-2-flash-sale-for-megamart/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-03-messaging-and-async-processing--week-03-preview Week 3 Preview: stop waiting, queue the work https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--week-03-preview/poster.jpg Why synchronous chains collapse under load, and how Week 3 decouples them: queues versus streams, the transactional outbox, backpressure, dead letters and poison pills, and an audit log that brings it all together. https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--week-03-preview/video.mp4 480 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-03-messaging-and-async-processing--day-01-queue-vs-stream Queue vs stream: work to be done, or things that happened? https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-01-queue-vs-stream/poster.jpg Why synchronous chains collapse, the two mental models of messaging, point-to-point, pub-sub and consumer groups, delivery and ordering guarantees, what goes wrong in production (crashes, rebalances, lag), how LinkedIn, Uber and webhook senders chose, and how to say it in an interview. https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-01-queue-vs-stream/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-03-messaging-and-async-processing--day-02-transactional-outbox Transactional outbox: two writes, made one https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-02-transactional-outbox/poster.jpg Why save-then-publish silently loses events, how the transactional outbox makes the database write and the event atomic, polling versus CDC, why publishing is still at-least-once, and the edge cases: a Kafka outage backlog, two publishers, out-of-order events, cleanup and monitoring. https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-02-transactional-outbox/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control Backpressure: when producers outrun consumers https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control/poster.jpg Why async pipelines have no natural brake, how to detect backpressure from lag, depth and latency, the four responses (shed, rate limit, scale, spill over) and the trilemma behind them, the edge cases of cascades, recovery herds and hot partitions, and how Netflix, LinkedIn and a surge-pricing pipeline cope. https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills Dead letters and poison pills: what to do with messages that won't process https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills/poster.jpg How one poison pill froze checkout for 4 hours, how to classify failures as transient, permanent or poison, the DLQ patterns (simple, categorized, delayed retry, error-specific), retry counts and retention, the edge cases that bite (DLQ consumers failing, replays breaking, infinite loops, duplicates), and safe replay for payments. https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-03-messaging-and-async-processing--day-05-audit-log-system Audit log system: every action, never lost, provably untouched https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-05-audit-log-system/poster.jpg A complete audit log for a financial company at 50,000 events a second with 7-year retention: outbox capture, Kafka transport, a consumer with backpressure and a DLQ, tiered storage, hash chaining for tamper evidence, the edge cases (outbox growth, lag, broken chains, clock skew), real-world variants, and a banking mock interview. Every Week 3 pattern in one system. https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--day-05-audit-log-system/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-03-messaging-and-async-processing--capstone-interview-week-3-event-driven-order-system Capstone: an event-driven food delivery order system, in 45 minutes https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--capstone-interview-week-3-event-driven-order-system/poster.jpg A full mock interview: clarify an order lifecycle across 50 cities, estimate 100 orders and 5,600 event deliveries a second, sketch an outbox-plus-Kafka architecture, then deep-dive into the outbox, dinner-rush backpressure, DLQs with compensation, and an audit trail for disputes, and finish with scaling, edge cases, monitoring and alerts. Every Week 3 idea in one answer. https://media.himanshukukreja.in/lectures/week-03-messaging-and-async-processing--capstone-interview-week-3-event-driven-order-system/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-04-caching--week-04-preview Caching: beyond just add Redis https://media.himanshukukreja.in/lectures/week-04-caching--week-04-preview/poster.jpg Why caching is deceptively hard, and a tour of Week 4: the four caching patterns, invalidation strategies, thundering herd defences, push versus pull feeds, and caches at every tier, tied back to Week 3's messaging. https://media.himanshukukreja.in/lectures/week-04-caching--week-04-preview/video.mp4 540 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-04-caching--day-01-caching-patterns Caching patterns: which one, and why? https://media.himanshukukreja.in/lectures/week-04-caching--day-01-caching-patterns/poster.jpg Why a flash sale took the site down, what caching buys you, the four patterns (cache-aside, read-through, write-through, write-behind) and when to use each, how a cache fails gracefully, and how to design a product catalog cache in an interview. https://media.himanshukukreja.in/lectures/week-04-caching--day-01-caching-patterns/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-04-caching--day-02-cache-invalidation Invalidation: getting stale data out https://media.himanshukukreja.in/lectures/week-04-caching--day-02-cache-invalidation/poster.jpg Why a flash sale showed the wrong price for an hour, the trilemma of freshness, simplicity and performance, TTL, event-driven and versioned invalidation, why delete beats update, the TTL safety net, leases, decomposed caching, and how to invalidate across regions. https://media.himanshukukreja.in/lectures/week-04-caching--day-02-cache-invalidation/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-04-caching--day-03-thundering-herd Thundering herd: taming the stampede https://media.himanshukukreja.in/lectures/week-04-caching--day-03-thundering-herd/poster.jpg How a single expired key took Black Friday down, the maths of the herd, five defences (locking, coalescing, probabilistic expiry, background refresh, stale-while-revalidate) and how to choose, the edge cases that break them, and how Instagram and a trending-topics design keep the database safe. https://media.himanshukukreja.in/lectures/week-04-caching--day-03-thundering-herd/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-04-caching--day-04-feed-caching Feed caching: push, pull, and the celebrity https://media.himanshukukreja.in/lectures/week-04-caching--day-04-feed-caching/poster.jpg Why a personalised feed is hard to cache, fan-out on write versus fan-out on read, the celebrity problem and the hybrid that solves it, ranking, sharding and warming, how Twitter, Instagram and LinkedIn choose, and how to design the Instagram feed in an interview. https://media.himanshukukreja.in/lectures/week-04-caching--day-04-feed-caching/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-04-caching--day-05-multi-tier-caching Multi-tier caching: every layer, one design https://media.himanshukukreja.in/lectures/week-04-caching--day-05-multi-tier-caching/poster.jpg How one request passes through five caches, what belongs at the browser, CDN, gateway and Redis, Cache-Control and Vary, why you invalidate from the inside out, caching for anonymous and logged-in users, and how Netflix and an AWS-style shop split their tiers. https://media.himanshukukreja.in/lectures/week-04-caching--day-05-multi-tier-caching/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-04-caching--capstone-interview-week-4-ecommerce-product-catalog Capstone: a global product catalog, cached https://media.himanshukukreja.in/lectures/week-04-caching--capstone-interview-week-4-ecommerce-product-catalog/poster.jpg A full interview on a global e-commerce catalog: requirements and freshness budgets, why the hit ratio must stay above 99%, the multi-tier architecture, flash-sale herd protection and warming, per-type invalidation, activity-tiered personalisation, the cache matrix, surviving a Redis outage, and how to monitor it all. https://media.himanshukukreja.in/lectures/week-04-caching--capstone-interview-week-4-ecommerce-product-catalog/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-05-consistency-and-coordination--week-05-preview Consistency and coordination: the cost of correct https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--week-05-preview/poster.jpg Where Week 4's stale caches stop being good enough: the last item sold twice, the transfer that loses money, the edit that vanishes and the two leaders, then a tour of Week 5 from consistency models to sagas, durable workflows, CRDTs and fenced locks. https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--week-05-preview/video.mp4 480 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-05-consistency-and-coordination--day-01-consistency-models Consistency models: who sees a write, and when https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-01-consistency-models/poster.jpg What consistent really means: the visibility question, the trade-off triangle, six models from linearizable to eventual, CAP stated correctly, a consistency-aware repository, DynamoDB, Spanner and TAO, quorums and their limits, isolation levels and locking, and a shopping cart interview. https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-01-consistency-models/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-05-consistency-and-coordination--day-02-saga-pattern Sagas: transactions without a shared rollback https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-02-saga-pattern/poster.jpg Why two-phase commit fails across microservices, how a saga replaces it with local transactions and compensations, choreography versus orchestration, the pivot and forward recovery, a crash-safe orchestrator with idempotency keys, booking and trip sagas, the mistakes that leave sagas stuck, and how to run them in production. https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-02-saga-pattern/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-05-consistency-and-coordination--day-03-saga-orchestration Durable execution: sagas that survive anything https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-03-saga-orchestration/poster.jpg Why a hand-built orchestrator is not enough, how Temporal records and replays workflow history, workflows versus activities and the determinism rules, task queues, signals and queries, state machines, versioning with patched, continue-as-new, activity timeouts, idempotent starts, Cadence and Conductor, and a loan-application interview. https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-03-saga-orchestration/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-05-consistency-and-coordination--day-04-conflict-resolution Conflict resolution: when two writes collide https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-04-conflict-resolution/poster.jpg The offline cart and the lost update, five resolution strategies, why last-write-wins loses data under clock skew, vector clocks and siblings, CRDTs from G-Counters to OR-Sets and text, replicating CRDT state, choosing a strategy per field, conflict detection, tombstone garbage collection, and an offline notes interview. https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-04-conflict-resolution/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-05-consistency-and-coordination--day-05-leader-election Leader election: exactly one in charge https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-05-leader-election/poster.jpg Why split-brain happens and timeouts cannot prevent it, fencing tokens checked where the write lands, consensus and Raft elections and terms, ZooKeeper and etcd election recipes, database leases, quorum re-confirmation, Kafka epochs, Redis Sentinel and Kubernetes leases, clock mistakes, and a cache-invalidation interview. https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--day-05-leader-election/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-05-consistency-and-coordination--capstone-interview-week-5-multiplayer-game-matchmaking-system Capstone: a matchmaking system that never double-books https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--capstone-interview-week-5-multiplayer-game-matchmaking-system/poster.jpg A full interview on multiplayer matchmaking: requirements and per-thing consistency, the numbers, the architecture and data flow, one fenced matchmaker per region, crash recovery, ratings with per-operation consistency, the match creation saga and its pivot, party membership as an OR-Set, scaling, failures, and how to monitor it. https://media.himanshukukreja.in/lectures/week-05-consistency-and-coordination--capstone-interview-week-5-multiplayer-game-matchmaking-system/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-06-designing-notification-platform--week-06-preview A notification platform: one system, five days https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--week-06-preview/poster.jpg Why Week 6 is different: one real system, a multi-channel notification platform for a fintech super-app, designed end to end across five days. The brief and its scale, how every Week 1 to 5 concept finds a job in it, one alert's journey, and a first taste of the interview dialogue and the edge cases ahead. https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--week-06-preview/video.mp4 420 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-06-designing-notification-platform--day-01-notification-platform-design Notification platform: understand it, then design it https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-01-notification-platform-design/poster.jpg Day 1 of the notification platform: how to open the interview with FERNS, the clarifying dialogue and the requirements read back, priorities and channel trade-offs, the channel selector and quiet hours, compliance penalties and rules, traffic, storage and provider cost, then the architecture, one notification traced end to end and through a push failure, why Kafka, the data layer, and idempotent, versioned APIs. https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-01-notification-platform-design/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-06-designing-notification-platform--day-02-core-notification-flow The core notification flow, end to end https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-02-core-notification-flow/poster.jpg Day 2 builds the happy path: an idempotent, validated Send API, the transactional outbox and its processor (skip locked, ack before mark, stop on failure), the router's preference, opt-out, quiet-hours and availability rules, templates with caching and locale fallback, one provider interface with retry and fallback flags, the channel worker loop with backoff and DLQ, multi-device push, the status state machine, and verified, deduplicated webhooks. https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-02-core-notification-flow/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-06-designing-notification-platform--day-03-advanced-features Advanced features: from good to great https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-03-advanced-features/poster.jpg Day 3 adds what separates good from great: A/B-tested template variants with consistent hashing, batching with count, time and hybrid flushes, timezone-aware digests, a leader-run scheduler with UTC storage and a best-time-to-send jitter, a multi-channel saga with fallback and escalation, an in-app notification center with an inbox, an unread counter and cross-server WebSocket delivery, and hierarchical, versioned preferences. https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-03-advanced-features/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-06-designing-notification-platform--day-04-scale-reliability-edge-cases Scale, reliability and edge cases: what breaks https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-04-scale-reliability-edge-cases/poster.jpg Day 4 breaks the platform on purpose: a 10 million campaign burst tamed by batched, throttled, isolated ingestion; celebrity fan-out done asynchronously and keyed by recipient; provider rate limits enforced by an atomic Redis limiter; circuit breakers and provider failover; the edge case encyclopedia (tokens, bounces, DST, races); failure modes and graceful degradation with hysteresis; and cost-aware channel selection. https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-04-scale-reliability-edge-cases/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-06-designing-notification-platform--day-05-operations-monitoring-interview Operations, monitoring and the interview https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-05-operations-monitoring-interview/poster.jpg Day 5 makes the platform operable: metrics at every stage, dashboards by persona, structured logs and a trace that shows where the time goes, alerts that page on symptoms and warn on causes, runbooks for low delivery, backlogs and open circuits, canary deploys and safe migrations, then the full 45-minute interview walkthrough, how Uber, Slack and WhatsApp do it, and the week's seven takeaways. https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--day-05-operations-monitoring-interview/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system Capstone: a food delivery order system, Weeks 1 to 6 https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system/poster.jpg A full 45-minute interview that uses every week so far: clarify a 5 million order a day platform, estimate 230 orders, 7,000 writes and 60,000 reads a second at peak, sketch an event-driven architecture, then deep-dive into an outbox with stable order IDs, idempotent Stripe payments, race-free driver assignment, an order saga with compensation, Redis GEO location tracking, rate limits and backpressure, and finish with 10x scaling, edge cases, monitoring, and what to build first. https://media.himanshukukreja.in/lectures/week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system/video.mp4 1320 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-07-designing-search-system--week-07-preview Search: making data findable at scale https://media.himanshukukreja.in/lectures/week-07-designing-search-system--week-07-preview/poster.jpg Why search is more than putting data in Elasticsearch: why SQL LIKE fails, the indexing, relevance and scale problems, the product search platform we build this week, its architecture and rough sizing, and how Weeks 1 to 6 feed into it. https://media.himanshukukreja.in/lectures/week-07-designing-search-system--week-07-preview/video.mp4 480 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-07-designing-search-system--day-01-search-fundamentals How search engines think https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-01-search-fundamentals/poster.jpg Why SQL LIKE dies on 50 million rows, the inverted index from first principles, the text analysis pipeline and why index and query must share an analyzer, field types and the multi-field pattern, Elasticsearch shards, node roles and scatter-gather, the search service, and sizing the cluster. https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-01-search-fundamentals/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-07-designing-search-system--day-02-indexing-pipeline Keeping search fresh https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-02-indexing-pipeline/poster.jpg Why dual-writing to PostgreSQL and Elasticsearch fails, change data capture with Debezium and Kafka, a batching, prioritised indexing pipeline with external versions, rate-limited and resumable bulk imports, zero-downtime reindexing with aliases, and the metrics, runbooks and delete patterns that keep it healthy. https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-02-indexing-pipeline/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-07-designing-search-system--day-03-query-processing-relevance Ranking the haystack https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-03-query-processing-relevance/poster.jpg How BM25 scores documents (term frequency with saturation, IDF, length normalisation) and how to tune it, query versus filter context and the filter cache, field, phrase, negative and business boosts, function scores and decay, multi-match types, progressive relaxation for no results, and the metrics that tell you if relevance is working. https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-03-query-processing-relevance/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-07-designing-search-system--day-04-advanced-search-features Building the search experience https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-04-advanced-search-features/poster.jpg Autocomplete with edge n-grams (and the completion suggester), did-you-mean that only corrects when it helps, facets with multi-select and category trees, synonyms and when to expand them, multi-language fields and analyzers, and personalisation that boosts without building a filter bubble. https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-04-advanced-search-features/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-07-designing-search-system--day-05-search-operations-scale Search that stays up https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-05-search-operations-scale/poster.jpg Running search in production: dedicated node roles and a quorum of masters, shard and capacity planning for growth and for a 5x Black Friday, pre-scaling and graceful degradation, the metrics and alerts that matter, snapshots and the five disaster scenarios, and the tuning checklist. https://media.himanshukukreja.in/lectures/week-07-designing-search-system--day-05-search-operations-scale/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-07-designing-search-system--capstone-interview-week-7-legal-document-search Capstone: legal document search https://media.himanshukukreja.in/lectures/week-07-designing-search-system--capstone-interview-week-7-legal-document-search/poster.jpg A full interview on search for law firms: requirements and estimates for 100 million documents, the architecture and upload flow, a parser for boolean and proximity queries, five layers of tenant isolation, a citation network in Elasticsearch, OCR ingestion, scaling to a billion documents, edge cases, monitoring, and what to build first. https://media.himanshukukreja.in/lectures/week-07-designing-search-system--capstone-interview-week-7-legal-document-search/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-08-designing-analytics-pipeline--week-08-preview Analytics: from raw events to answers https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--week-08-preview/poster.jpg Why Week 8 turns from systems that serve data to systems that understand it: the volume, velocity and accuracy problem, the pipeline from ingestion to dashboards, event schemas, Lambda versus Kappa, late data, query optimisation, and the week's plan. https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--week-08-preview/video.mp4 480 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-08-designing-analytics-pipeline--day-01-event-ingestion Event ingestion: capture everything, drop nothing https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-01-event-ingestion/poster.jpg How to capture every meaningful action reliably at scale: events as immutable facts, the event envelope and safe schema evolution, the collection API, validation and best-effort enrichment, Kafka topics, keys and producer guarantees, backpressure and load shedding, multi-region collection, and the mistakes to avoid. https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-01-event-ingestion/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-08-designing-analytics-pipeline--day-02-streaming-vs-batch Streaming vs batch: now, or exactly? https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-02-streaming-vs-batch/poster.jpg When to stream, when to batch, and how to do both: the latency, accuracy and cost trade-off, Lambda's batch and speed layers and its two-codebase problem, Kappa's replay and its big question, how to choose, Flink windows, watermarks and state, Spark batch jobs, unified APIs, and the mistakes that produce wrong numbers. https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-02-streaming-vs-batch/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-08-designing-analytics-pipeline--day-03-data-modeling Data modeling: designing for queries https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-03-data-modeling/poster.jpg How to model data so analytics stays fast over billions of rows: OLTP against OLAP, the star schema with facts, dimensions and grain, slowly changing dimensions and point-in-time accuracy, columnar formats, partitioning and Z-ordering, rollups and materialized views, the ETL load order, and the classic modeling mistakes. https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-03-data-modeling/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-08-designing-analytics-pipeline--day-04-late-data Late data: when real-time isn't real-time https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-04-late-data/poster.jpg Why numbers change after the fact and how to keep trust: event time against processing time, watermarks and their strategies, sizing lateness from a measured distribution, windows and late events, patching against reprocessing, versioned results, a production pipeline with daily finalization, T+1 and T+7 reporting, and the dashboard mistakes to avoid. https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-04-late-data/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-08-designing-analytics-pipeline--day-05-query-optimization The query layer: making big data feel small https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-05-query-optimization/poster.jpg How to make dashboard queries over billions of rows fast and affordable: choosing among warehouses, real-time OLAP, lake engines and embedded engines, why queries are slow, partitioning and clustering, when to pre-aggregate and how to route to rollups, materialized views, multi-layer caching with TTLs by freshness, multi-tenant isolation and quotas, a production query service, and the cost mistakes to avoid. https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--day-05-query-optimization/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics Capstone: analytics for a streaming platform https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics/poster.jpg A full interview on real-time analytics for a video streaming service: clarifying questions, a million events a second and a petabyte of data, the Kafka, Flink, Spark, ClickHouse and BigQuery architecture, the event envelope and regional ingestion, a trending score from unique viewers, late data from planes and subways with real-time, preliminary and final numbers, a star schema for creators, query layers, scaling 10 times, edge cases and monitoring. https://media.himanshukukreja.in/lectures/week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-09-multi-tanency-security--week-09-preview Multi-tenancy, security and compliance: building for trust https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--week-09-preview/poster.jpg Why a system built for scale can still fail an enterprise security questionnaire, and the week ahead: the tenant isolation spectrum, noisy neighbours, data residency under GDPR, deletion across many systems, defence in depth, and the HR SaaS capstone. https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--week-09-preview/video.mp4 480 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-09-multi-tanency-security--day-01-tenant-isolation Tenant isolation: thousands of customers, one platform https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-01-tenant-isolation/poster.jpg The isolation spectrum from shared tables to separate cloud accounts, the three database patterns and their costs, tenant context taken from auth and carried through every layer, PostgreSQL row-level security and its traps, real hybrids from Slack, Salesforce and AWS, and how to prove isolation with tests. https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-01-tenant-isolation/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-09-multi-tanency-security--day-02-noisy-neighbour Noisy neighbours: one tenant must never ruin it for everyone https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-02-noisy-neighbour/poster.jpg How one legitimate export took 500 tenants down, the six resources a tenant can exhaust, layered defences from gateway to infrastructure, token buckets and a shared Redis limiter, tiered quotas, query guards, per-tenant pools, fair scheduling, and lessons from Salesforce, Stripe and AWS. https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-02-noisy-neighbour/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-09-multi-tanency-security--day-03-data-residency Data residency and GDPR: the right data in the right place https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-03-data-residency/poster.jpg Why a German customer's legal letter forces a re-architecture: residency versus sovereignty, what counts as personal data, four regional patterns and per-tenant routing, lawful basis and recorded consent, cross-border transfers after Schrems II, DPAs and subprocessors, Slack's and AWS's approaches, and the mistakes that leak data across borders. https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-03-data-residency/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-09-multi-tanency-security--day-04-right-to-deletion Right to deletion: erasing a user from dozens of systems, and proving it https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-04-right-to-deletion/poster.jpg What GDPR Article 17 requires and when you may refuse, why deletion is hard, hard versus soft delete versus anonymisation, the data inventory, an ordered and retryable deletion orchestrator with verification, backups that expire and restores that re-apply deletions, the compliance report, and how Stripe and Slack handle it. https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-04-right-to-deletion/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-09-multi-tanency-security--day-05-security-architecture Security architecture: defence in depth for a multi-tenant system https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-05-security-architecture/poster.jpg From a database password committed to main: defence in depth, zero trust and least privilege, trust boundaries and STRIDE, encryption in transit, at rest and per field with a key hierarchy, secrets in a vault with rotation, login, tokens and revocable sessions, tenant-first authorisation, Stripe and BeyondCorp, and incident response. https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--day-05-security-architecture/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-09-multi-tanency-security--capstone-interview-week-9-multi-tenant-saas Capstone: a multi-tenant enterprise document platform, in 45 minutes https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--capstone-interview-week-9-multi-tenant-saas/poster.jpg A full mock interview: clarify 500 tenants across three regions, estimate 50 TB, 1,000 requests a second and a 3 TB index, sketch regional data planes under a metadata-only control plane, then deep-dive into five isolation layers, quotas and fair queues, residency and export, ordered deletion, and layered security, and finish with 10x scaling, edge cases, per-tenant monitoring and alerts. Every Week 9 idea in one answer. https://media.himanshukukreja.in/lectures/week-09-multi-tanency-security--capstone-interview-week-9-multi-tenant-saas/video.mp4 1260 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-10-production-readiness-and-operational-excellence--week-10-preview Week 10 preview: from building to operating https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--week-10-preview/poster.jpg The final week: why designing a system isn't the same as running it, the six pillars of production readiness, a tour of SLOs, observability, safe deployment, capacity planning and incident management, the real-time bidding capstone, and the mindset shift from "I built it" to "I can operate it". https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--week-10-preview/video.mp4 480 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas SLIs, SLOs and SLAs: defining healthy https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas/poster.jpg Why reliability needs precise language, the SLI to SLO to SLA ladder, the four golden signals and a precise SLI spec, why the goal is appropriate rather than maximum reliability, error budgets and their policies, multi-window burn rate alerting, dependency chains, tiered SLOs, and how to talk about it all in an interview. https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas/video.mp4 1140 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-10-production-readiness-and-operational-excellence--day-02-observability Observability: seeing inside production https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-02-observability/poster.jpg From a 3:47 AM page to a root cause in five minutes: monitoring versus observability, the three pillars and how a trace ID ties them together, metric types and the cardinality trap, RED and USE, structured logs and what never to log, distributed tracing and context propagation, the observability stack, dashboards, symptom-based alerts and runbooks, and a live debugging interview. https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-02-observability/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies Deployment strategies: shipping without breaking https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies/poster.jpg The deployment paradox and why small, frequent deploys win; big bang, rolling, blue-green and canary compared; automated canary analysis and rollback thresholds; feature flags and consistent bucketing; expand-contract schema migrations; the four kinds of rollback; how Amazon and Google deploy; and how to talk about it in an interview. https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-10-production-readiness-and-operational-excellence--day-04-capacity-planning Capacity planning: scaling before you need to https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-04-capacity-planning/poster.jpg From a Friday-night 5x surprise to a plan: the measure-forecast-identify-plan-validate cycle, headroom and its bands, finding the breaking point, forecasting with lead time, bottlenecks, Little's Law and the queueing spiral, five kinds of load test, scaling up versus out, auto-scaling policy and lag, Netflix and Stripe, and a dinner-rush capacity interview. https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-04-capacity-planning/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-10-production-readiness-and-operational-excellence--day-05-incident-management Incident management: when things go wrong https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-05-incident-management/poster.jpg From a 3:17 AM page to a blameless postmortem: what counts as an incident, severity levels, the lifecycle and its four clocks, incident roles, sustainable on-call and what should page, handoffs, the mitigation decision tree and runbooks, five whys, the postmortem, communicating inside and out, how Google and Stripe respond, and prevention. https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--day-05-incident-management/video.mp4 1080 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale The grand finale: a global real-time bidding platform https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale/poster.jpg The course's final interview: a 100 ms, 500,000 request-a-second ad auction across six continents. Requirements, estimates and a latency budget; the regional architecture and one request end to end; hierarchical budget leases that never overspend; DSP fan-out with circuit breakers and load shedding; a transactional-outbox audit trail and tiered storage; tiered fraud detection; Super Bowl scale and edge cases; SLOs and dashboards; and a send-off for the whole course. https://media.himanshukukreja.in/lectures/week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale/video.mp4 1200 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-05-paisly-otp-login Mock interview: phone OTP sign-in and sessions at Paisly https://media.himanshukukreja.in/lectures/mock-interviews--mock-05-paisly-otp-login/poster.jpg A full 45-minute model interview: Siddharth splits sign-in into its four paths, finds that the Diwali sale needs both SMS providers live, stores the OTP as an HMAC with capped guesses, uses signed tokens with a pushed deny list for lost phones, fails over on delivery receipts, fixes a replica-lag bug and a hot celebrity number, and pushes back on 7-day sessions with numbers. https://media.himanshukukreja.in/lectures/mock-interviews--mock-05-paisly-otp-login/video.mp4 2820 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-01-billbolt-autopay Mock interview: bill payments and AutoPay at Billbolt https://media.himanshukukreja.in/lectures/mock-interviews--mock-01-billbolt-autopay/poster.jpg A full 45-minute model interview: Vikram clarifies who confirms what, finds BillHub's 300 req/s as the real bottleneck, makes the pay call idempotent, contains a failing biller with per-biller breakers, makes AutoPay safe to run twice with unique runs and fencing tokens, and redoes the maths when AutoPay grows tenfold. https://media.himanshukukreja.in/lectures/mock-interviews--mock-01-billbolt-autopay/video.mp4 2880 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-06-cartwala-flash-sale-catalog Mock interview: the Noon Drop at Cartwala https://media.himanshukukreja.in/lectures/mock-interviews--mock-06-cartwala-flash-sale-catalog/poster.jpg A full 50-minute model interview: Arjun splits browsing a price from charging one, proves with numbers that flushing the cache at 12:00 can't work, stores each product's price timeline in the cache so the flip needs no invalidation, pins the deal of the day in every pod's memory, survives a Redis shard dying mid-sale, re-prices every order from the primary through a pricing mistake, and keeps a poisoned price queue from ever causing a wrong charge. https://media.himanshukukreja.in/lectures/mock-interviews--mock-06-cartwala-flash-sale-catalog/video.mp4 2820 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-02-wanderstay-bookings Mock interview: stays booking and availability at Wanderstay https://media.himanshukukreja.in/lectures/mock-interviews--mock-02-wanderstay-bookings/poster.jpg A full 50-minute model interview: Sara splits a 250-to-1 look-to-book system into a stale-but-fast search path and an exact booking path, claims all nights in one conditional update, survives a thundering herd and a payment timeout, rejects last-write-wins on channel updates, and turns overbooking into a measured 10× goal. https://media.himanshukukreja.in/lectures/mock-interviews--mock-02-wanderstay-bookings/video.mp4 3120 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-07-sunwaai-support-desk Mock interview: the support desk at Sunwaai https://media.himanshukukreja.in/lectures/mock-interviews--mock-07-sunwaai-support-desk/poster.jpg A full 50-minute model interview: Meghna sizes a multi-tenant help desk, feeds near-real-time ticket search from an outbox stream with external versions, makes search permission-aware and closes a stale-permission snippet leak, fires SLA timers once, tames a 200,000-ticket complaint storm with quotas and incident mode, and answers an EU residency request by reusing the tenant partition key. https://media.himanshukukreja.in/lectures/mock-interviews--mock-07-sunwaai-support-desk/video.mp4 2880 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-03-kaamkaaj-job-search Mock interview: job search, alerts and analytics at Kaamkaaj https://media.himanshukukreja.in/lectures/mock-interviews--mock-03-kaamkaaj-job-search/poster.jpg A recorded 50-minute senior system design round with Kabir Sethi at Kaamkaaj: scoping three systems, sizing a small index and a huge event stream, CDC-fed search, a shared notification platform that turns a 20,000-job burst into one push, percolator alerts, event-time analytics with late data, recruiter isolation, the applies mismatch and a safe reindex. https://media.himanshukukreja.in/lectures/mock-interviews--mock-03-kaamkaaj-job-search/video.mp4 3120 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-08-switchyard-feature-flags Mock interview: feature flags at Switchyard https://media.himanshukukreja.in/lectures/mock-interviews--mock-08-switchyard-feature-flags/poster.jpg A full 50-minute staff-level model interview: Tejas asks where evaluation happens before anything else, proves with numbers that SDKs must evaluate locally and that the control plane is tiny next to the data plane, makes bucketing sticky and identical in every language, streams deltas through the edge, budgets and proves a 5-second kill switch, refuses to trust last year's empty ruleset, protects experiments from reallocation, late data and sample ratio mismatch, contains a leaked SDK key, and turns a bank's demand for its own everything into a dedicated cell, BYOK and a relay proxy. https://media.himanshukukreja.in/lectures/mock-interviews--mock-08-switchyard-feature-flags/video.mp4 2880 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/mock-interviews--mock-04-tillsy-pos-platform Mock interview: the offline-first POS platform at Tillsy https://media.himanshukukreja.in/lectures/mock-interviews--mock-04-tillsy-pos-platform/poster.jpg A recorded staff-level final loop with Dr. Meera Iyer at Tillsy: billing that never needs the cloud, the reconnect storm, an idempotent versioned sync protocol, conflict rules without device clocks, regions and cells, a dedicated-cell deal, no-bill-lost guarantees, GDPR erasure against tax retention, a Diwali incident and the biggest risk in the design. https://media.himanshukukreja.in/lectures/mock-interviews--mock-04-tillsy-pos-platform/video.mp4 2880 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-01-indian-upi-system India's UPI: where's the money when a bank times out? https://media.himanshukukreja.in/lectures/bonus-01-indian-upi-system/poster.jpg How UPI's switch routes about 800 million payments a day between 740+ banks without ever holding the money, and how it stays safe when a credit times out halfway, a bank goes down, or status checks flood the switch. https://media.himanshukukreja.in/lectures/bonus-01-indian-upi-system/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-02-whatsapp-messaging WhatsApp: one hello, three ticks, nobody in between reads it https://media.himanshukukreja.in/lectures/bonus-02-whatsapp-messaging/poster.jpg How WhatsApp's chat servers carry 100 billion end-to-end encrypted messages a day to 50 million connected phones without ever reading one, why the server is a delivery queue and not an archive, and how a message to an offline phone survives a dropped sync with no gaps and no duplicates. https://media.himanshukukreja.in/lectures/bonus-02-whatsapp-messaging/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-03-aadhar-identity-system Aadhaar: a lookup in 200 ms, a search across 1.45 billion https://media.himanshukukreja.in/lectures/bonus-03-aadhar-identity-system/poster.jpg How Aadhaar verifies any of 1.45 billion people in under 200 milliseconds while proving nobody enrols twice, by building one-to-one authentication and one-to-N deduplication as two separate paths, and how it protects fingerprints that can never be reset. https://media.himanshukukreja.in/lectures/bonus-03-aadhar-identity-system/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-04-visa-mastercard-payments Visa and Mastercard: an approval is a promise, not a payment https://media.himanshukukreja.in/lectures/bonus-04-visa-mastercard-payments/poster.jpg How a card network routes about 434 billion authorizations a year to roughly 14,500 issuing banks inside a sliver of a 2-second checkout, why no money moves until netted settlement a day or two later, and how tiered timeouts, stand-in and one idempotency key keep a silent bank or a retry from failing or double-charging anyone. https://media.himanshukukreja.in/lectures/bonus-04-visa-mastercard-payments/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-05-google-search Google Search: a thousand shards, and the slowest one sets the pace https://media.himanshukukreja.in/lectures/bonus-05-google-search/poster.jpg How a search engine answers three words against tens of billions of pages in under 500 milliseconds: an inverted index sharded by document, a query that fans out to every shard under strict stage budgets, deadlines and hedged requests for the slow tail, crawling kept off the clock, and a fresh tier for breaking news. https://media.himanshukukreja.in/lectures/bonus-05-google-search/video.mp4 780 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-06-netflix-streaming Netflix: the cloud decides, the ISP delivers https://media.himanshukukreja.in/lectures/bonus-06-netflix-streaming/poster.jpg How Netflix starts any title in under 2 seconds for about 10 million concurrent streams: AWS only decides what to play, appliances inside ISPs filled off-peak deliver 50 terabits a second, the player adapts quality chunk by chunk, and breakers, ranked failover URLs and request coalescing keep it degrading instead of failing. https://media.himanshukukreja.in/lectures/bonus-06-netflix-streaming/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-07-spotify-streaming Spotify: any song in 200 milliseconds https://media.himanshukukreja.in/lectures/bonus-07-spotify-streaming/poster.jpg How Spotify starts any of 100M+ tracks in under 200 ms for 777M monthly users: audio from the device or a CDN edge behind a signed URL, recommendations behind breakers off the play path, and play events counted exactly once with a play ID and event time. https://media.himanshukukreja.in/lectures/bonus-07-spotify-streaming/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-08-AWS-S3 AWS S3: never lose one of 500 trillion https://media.himanshukukreja.in/lectures/bonus-08-AWS-S3/poster.jpg How S3 keeps 500 trillion+ objects at 11 nines of durability and 200M+ requests a second: a partitioned index kept apart from 10 + 6 erasure-coded bytes spread across three AZs, fast repair, a witness check that makes every read see the latest write, prefix partitions that split on load, and versioning and Object Lock for the deletes durability can't stop. https://media.himanshukukreja.in/lectures/bonus-08-AWS-S3/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-09-uber Uber: the right car in under 3 seconds https://media.himanshukukreja.in/lectures/bonus-09-uber/poster.jpg How Uber matches a rider to a driver in under 3 s while ~500K driver pings a second land at peak: live locations as soft state in an H3 hexagon index in Redis, trips created exactly once in Spanner, ETA-led scoring with one PENDING offer at a time, per-cell smoothed surge, and a failover that replicates trips and rebuilds locations. https://media.himanshukukreja.in/lectures/bonus-09-uber/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-10-twitter-x Twitter/X: a post in every timeline in 5 seconds https://media.himanshukukreja.in/lectures/bonus-10-twitter-x/poster.jpg How Twitter/X puts ~500M posts a day into followers' home timelines within 5 s and serves ~300K timeline reads a second from memory: push tweet IDs at write time for ordinary authors, pull celebrity posts at read time, cache IDs not tweets, degrade by delay in a spike, and delete with a tombstone filtered at hydration. https://media.himanshukukreja.in/lectures/bonus-10-twitter-x/video.mp4 720 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-11-irctc-booking-system IRCTC Tatkal: 500 seats, 2 million hands https://media.himanshukukreja.in/lectures/bonus-11-irctc-booking-system/poster.jpg How a ~500-seat Tatkal quota opens to ~2 million people at 10:00:00 and sells each seat exactly once: a waiting room that admits only what the core can absorb, a dumb atomic Redis counter per pool that says no to 99.975% in milliseconds, a single-writer allocator, a hold-then-pay saga where a payment timeout becomes DEEMED_PENDING, and search kept on a separate plane. https://media.himanshukukreja.in/lectures/bonus-11-irctc-booking-system/video.mp4 780 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-12-blinkit-quick-commerce Blinkit: where do the ten minutes come from? https://media.himanshukukreja.in/lectures/bonus-12-blinkit-quick-commerce/poster.jpg How a quick-commerce platform gets a basket from a dark store about 2 km away to the door in about ten minutes, across 2,443 stores and millions of orders a day: win the minutes inside the store, reserve stock exactly at checkout, trust the shelf over the count, and show each customer an estimate the store can actually keep. https://media.himanshukukreja.in/lectures/bonus-12-blinkit-quick-commerce/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-13-zerodha-kite-trading Zerodha Kite: one tap, one order, at 9:15:00 https://media.himanshukukreja.in/lectures/bonus-13-zerodha-kite-trading/poster.jpg How a broker platform survives the 9:15 open: orders, prices and reads on three paths sized for what each can lose, one idempotency key per tap, an UNKNOWN state reconciled with the exchange instead of a resend, one margin writer per account, and binary price snapshots fanned out to 1.5 million screens. https://media.himanshukukreja.in/lectures/bonus-13-zerodha-kite-trading/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-14-chatgpt-llm-serving ChatGPT: one token at a time, for a billion people https://media.himanshukukreja.in/lectures/bonus-14-chatgpt-llm-serving/poster.jpg How an LLM serving stack streams replies to over a billion weekly users: count tokens and GPU memory instead of requests, batch hundreds of replies into every decode step with continuous batching and paged KV memory, route conversations to their cached prefix, never pay the GPU twice for a dropped stream, and choose fairly when demand beats capacity. https://media.himanshukukreja.in/lectures/bonus-14-chatgpt-llm-serving/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-15-figma-multiplayer Figma multiplayer: one file, two hundred editors https://media.himanshukukreja.in/lectures/bonus-15-figma-multiplayer/poster.jpg How a design tool lets up to 500 people edit one file at once: one owner server per file that holds it in memory and orders every property change, last-writer-wins per property, optimistic edits that never flicker, an outbox and a fenced journal so nothing anyone saw is lost, and cursors on their own cheap, lossy path. https://media.himanshukukreja.in/lectures/bonus-15-figma-multiplayer/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-16-bookmyshow-seat-booking BookMyShow: four seats in row H, and 13 million at noon https://media.himanshukukreja.in/lectures/bonus-16-bookmyshow-seat-booking/poster.jpg How a ticketing platform lets millions pick exact seats from a live map without ever selling one twice: one writer per show holding all the seats or none, holds that are states with their expiry on the seat, partner seats held by asking with our hold id, and a waiting-room front door that keeps 13 million people waiting cheaply and fairly. https://media.himanshukukreja.in/lectures/bonus-16-bookmyshow-seat-booking/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-17-swiggy-food-delivery Swiggy: which rider, and when should they start riding? https://media.himanshukukreja.in/lectures/bonus-17-swiggy-food-delivery/poster.jpg How a food-delivery platform gets about 2 million orders a day from kitchens it doesn't run to doors across the city: dispatching riders just in time for a predicted ready time, matching them in 20-second rounds per city, putting a clock on every kitchen step, and promising a calibrated quantile instead of an average. https://media.himanshukukreja.in/lectures/bonus-17-swiggy-food-delivery/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-18-razorpay-payment-gateway Razorpay: charging exactly once when the bank never answers https://media.himanshukukreja.in/lectures/bonus-18-razorpay-payment-gateway/poster.jpg How a payment gateway taking over a billion payments a quarter gives every one exactly one final outcome: idempotency records and guarded state transitions, an UNKNOWN state resolved by status checks and settlement files, routing per slice, a double-entry ledger, and webhooks delivered at least once. https://media.himanshukukreja.in/lectures/bonus-18-razorpay-payment-gateway/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-19-youtube-video-platform YouTube: an upload on a train, and a view count nobody can fake https://media.himanshukukreja.in/lectures/bonus-19-youtube-video-platform/poster.jpg How a video platform takes 20 million+ uploads a day over flaky connections, turns each into playable video within minutes, counts views honestly at millions a second, and picks 20 videos out of 20 billion in 100 ms: resumable uploads, chunked task graphs, view events with per-playback IDs, and two-stage recommendations. https://media.himanshukukreja.in/lectures/bonus-19-youtube-video-platform/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-20-google-docs-collaboration Google Docs: two people, one sentence, the same text https://media.himanshukukreja.in/lectures/bonus-20-google-docs-collaboration/poster.jpg How up to 100 people type into the same document and every screen ends up identical: small changes against numbered revisions, operational transformation on one server per document, one change in flight per client, a revision log that is the document, its fence and its history, and composition for long offline sessions. https://media.himanshukukreja.in/lectures/bonus-20-google-docs-collaboration/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-21-instagram-feed Instagram: twenty posts out of thousands, in half a second https://media.himanshukukreja.in/lectures/bonus-21-instagram-feed/poster.jpg How a feed and stories tray for 3 billion monthly users stays fast: media stored once and served from caches, small time-sortable IDs fanned out on write for most accounts and pulled for the huge ones, ranking as a funnel of filters and models, and stories that leave the tray when an index entry expires. https://media.himanshukukreja.in/lectures/bonus-21-instagram-feed/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-22-google-maps Google Maps: the fastest route on roads that keep changing https://media.himanshukukreja.in/lectures/bonus-22-google-maps/poster.jpg How directions, live traffic and the map work for 2 billion monthly users: a road graph partitioned once into cells with a shortcut overlay whose costs are re-customized from live speeds in under a second, phone fixes map-matched into per-segment speeds within about two minutes, arrival times that time each road for when the driver reaches it, and vector tiles named by quadkey under immutable, versioned URLs. https://media.himanshukukreja.in/lectures/bonus-22-google-maps/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-23-zoom-video-meetings Zoom: fourteen people, three continents, one room https://media.himanshukukreja.in/lectures/bonus-23-zoom-video-meetings/poster.jpg How video meetings work for 300 million daily meeting participants: a small, ordered control plane with one controller per meeting, kept apart from a media plane of routers that forward packets without decoding them, senders that send layers so each router can pick one per receiver from its bandwidth estimate, UDP with forward error correction, resends and jitter buffers and TLS on 443 through firewalls, and participants placed in their nearest zone with routers cascading across regions. https://media.himanshukukreja.in/lectures/bonus-23-zoom-video-meetings/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-24-airbnb-stays-marketplace Airbnb: a marketplace of nine million one-of-a-kind homes https://media.himanshukukreja.in/lectures/bonus-24-airbnb-stays-marketplace/poster.jpg How a stays marketplace with 9 million+ listings and 533 million nights a year works: search leaves that hold every listing's geo cell, a 365-night availability bit array and prices in memory, filtering by place then dates before a retrieve, rank and re-rank funnel and map pins chosen for attention; a unique key per listing-night at Reserve; iCal calendars from other sites polled by risk, diffed by source and refreshed when a guest presses Reserve; Smart Pricing inside the host's range; and guests' money held in a double-entry ledger and paid out the business day after check-in with an idempotency key per payout. https://media.himanshukukreja.in/lectures/bonus-24-airbnb-stays-marketplace/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-25-dream11-fantasy-sports Dream11: fifteen million people, thirty minutes after the toss https://media.himanshukukreja.in/lectures/bonus-25-dream11-fantasy-sports/poster.jpg How a fantasy sports platform at IPL scale works: 15.01 million concurrent users and 308 million requests a minute, with joins and team edits packed into the 30 minutes between the toss and the deadline; capacity forecast days ahead and added an hour before, with tiered load shedding that protects team saves and joins; mega contests that take spots from sharded counters so they can't be oversold, and templates that keep small contests open; a deadline that is one state flip checked atomically by every write; live points recomputed from versioned ball records for each distinct lineup; exact ranks from half-point histograms with ties sharing a rank; and keyed ledger postings for prizes, refunds and withdrawals with 30% tax deducted on net winnings. https://media.himanshukukreja.in/lectures/bonus-25-dream11-fantasy-sports/video.mp4 780 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-26-truecaller-caller-id Truecaller: naming a stranger before the second ring https://media.himanshukukreja.in/lectures/bonus-26-truecaller-caller-id/poster.jpg How caller ID and spam detection work for hundreds of millions of phones: 500 million+ users and 411.1 million daily users outside iOS (Q3 2026, preliminary), 68 billion+ spam calls identified and blocked in 2025; a read path where the phone answers first and the network is asked once, with a deadline, for a precomputed serving record; hash-partitioned, regionally replicated records with hot numbers kept as cache copies that are overwritten, never deleted; a crowd-written directory scored by weighing evidence (call proof, reporter trust, distinct reporters) in a stream, with weights from a daily batch; a signed regional spam list on the phone as a base plus deltas; private iPhone lookups through an Oblivious HTTP relay, Privacy Pass tokens and PIR over sharded data in memory; and the consent question, with Truecaller's statements, its critics, a 2026 Lagos ruling, India's DPDP Rules, unlisting within 24 hours and lineage on every name. https://media.himanshukukreja.in/lectures/bonus-26-truecaller-caller-id/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-27-flipkart-big-billion-days Flipkart Big Billion Days: six million shoppers, five thousand phones https://media.himanshukukreja.in/lectures/bonus-27-flipkart-big-billion-days/poster.jpg How a national sale event works at Flipkart's scale: 6.3 million concurrent users in a minute in the 2026 opening hour, six to eight times the usual transactions and nearly 1,000 times the payment requests at the festive peak; a cached read plane and a small, exact write plane; the sale staged as a version so midnight is one pointer flip, with jittered refreshes instead of synchronised expiry; a line per deal at the edge, with a two-second lottery, tokens at the units times 1.3 and an honest answer for everyone else; stock held at checkout with expiring, keyed holds that are extended while money is in flight; unknown payment outcomes reconciled with the same key and confirmed orders written with an outbox; versioned price books that fail closed; and delivery dates backed by reserved wave capacity, answering each line of the founders' 2014 apology. https://media.himanshukukreja.in/lectures/bonus-27-flipkart-big-billion-days/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-28-gmail-email-at-scale Gmail: say yes to the whole internet, and never lose a message https://media.himanshukukreja.in/lectures/bonus-28-gmail-email-at-scale/poster.jpg How an email service for 1.5 billion mailboxes works: an SMTP edge that refuses cheaply and answers 250 OK only after a quorum write in two zones, with message keys for retries and 451 deferrals as backpressure; a filter funnel that treats authentication as identity and lets reputation, content and user reports judge, on a classifier whose move to RETVec raised detection by 38 percent; SPF, DKIM, DMARC alignment and Gmail's 2024 rules for senders of more than 5,000 a day; metadata apart from content-addressed blobs, erasure-coded as they age, with slow purges, cell-by-cell rollouts and an offline copy after the 2011 tape restore; one search index per mailbox; and quotas and receiving limits that defer with temporary failures. https://media.himanshukukreja.in/lectures/bonus-28-gmail-email-at-scale/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-29-github-code-hosting GitHub: a billion repositories, and a push that lands on a majority or not at all https://media.himanshukukreja.in/lectures/bonus-29-github-code-hosting/poster.jpg How a code host at GitHub's scale works: a billion repositories on five replicas each, where Spokes accepts a reference update only when a strict majority applies it with matching checksums, so there is no primary to fail over; a 2026 move, now rolling out, from a repository-wide lock to a quorum per reference, with Azure Blob Storage as a virtual replica next; reads sent to the nearest in-sync replica and fileservers drained before reboots; one Kafka event per push fanned out to consumers with their own retry rules; webhooks with a 10-second timeout, per-host isolation and delivery ids; 124 million Actions jobs a day on fresh VMs with per-account queues, fair share and leases with epochs; and code search sharded by Git blob id, with permissions checked twice. https://media.himanshukukreja.in/lectures/bonus-29-github-code-hosting/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/bonus-30-tiktok-for-you-feed TikTok's For You feed: learning from every swipe within minutes https://media.himanshukukreja.in/lectures/bonus-30-tiktok-for-you-feed/poster.jpg How a short-video For You feed can learn from every swipe: more than a billion people a month (TikTok, 2021) and, on stated assumptions, about a million impressions a second at peak, each one a label; watch time judged against videos of the same length, with quick skips as strong negatives; the exact features served logged and joined with labels in a streaming joiner, with late labels waiting on disk and a log odds correction for sampled negatives, as in ByteDance's Monolith paper; collisionless embedding tables with admission and expiry; touched rows synced to serving every minute and dense weights daily; new videos given staged exposure on evidence, not followers; and a re-rank that keeps TikTok's published diversity rules. An illustrative design: TikTok hasn't published its architecture, and ByteDance's papers don't name TikTok. https://media.himanshukukreja.in/lectures/bonus-30-tiktok-for-you-feed/video.mp4 1020 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-01-url-shortener URL shortener: seven characters, every decision showing https://media.himanshukukreja.in/lectures/problem-bank--problem-01-url-shortener/poster.jpg One strong interview answer to "design bit.ly": a read-path problem with a tiny write path, codes from leased ID blocks scrambled and base-62 encoded, 302 redirects made cheap with cache-aside, negative caching and async click counts, and what to do when Redis or the allocator fails. https://media.himanshukukreja.in/lectures/problem-bank--problem-01-url-shortener/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-02-rate-limiter Rate limiter: a counter, a clock and a decision in 2 ms https://media.himanshukukreja.in/lectures/problem-bank--problem-02-rate-limiter/poster.jpg One strong interview answer to "design a rate limiter": a sliding window counter in Redis, checked and incremented in one atomic script, shared by 40 gateways; a local deny cache so one abusive client can't melt its shard; and failing open so a limiter outage never becomes an API outage. https://media.himanshukukreja.in/lectures/problem-bank--problem-02-rate-limiter/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-03-key-value-store Key-value store: two calls, and everything behind them https://media.himanshukukreja.in/lectures/problem-bank--problem-03-key-value-store/poster.jpg One strong interview answer to "design a distributed key-value store": a hash ring with virtual nodes for placement, R + W > N quorums tuned per request, sloppy quorums and hinted handoff to stay writable, vector clocks so two carts merge instead of losing an item, and the tombstones that stop deletes coming back. https://media.himanshukukreja.in/lectures/problem-bank--problem-03-key-value-store/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-04-unique-id-generator Unique IDs: 64 bits, a million a second, no two alike https://media.himanshukukreja.in/lectures/problem-bank--problem-04-unique-id-generator/poster.jpg One strong interview answer to "design a unique ID generator": a Snowflake-style 64-bit layout of time, worker and sequence built inside each service with no network call, worker IDs held as etcd leases so no two instances share one, and what to do when a clock goes backwards, a VM wakes up late, or a browser rounds your ID. https://media.himanshukukreja.in/lectures/problem-bank--problem-04-unique-id-generator/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-05-web-crawler Web crawler: a billion pages, politely, without getting lost https://media.himanshukukreja.in/lectures/problem-bank--problem-05-web-crawler/poster.jpg One strong interview answer to "design a web crawler": a two-layer frontier where priority decides what to fetch and per-host queues decide when, URL normalisation and a 12 GB Bloom filter for the seen set, SimHash for near-duplicate pages, defences against spider traps, and the robots.txt and lease rules that keep it polite and robust. https://media.himanshukukreja.in/lectures/problem-bank--problem-05-web-crawler/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-06-notification-system Notifications: the OTP never waits behind the sale https://media.himanshukukreja.in/lectures/problem-bank--problem-06-notification-system/poster.jpg One strong interview answer to "design a notification system": one send API that stores and queues atomically with an outbox, a router that applies preferences and quiet hours, at-least-once delivery made harmless with idempotency and dedupe keys, breakers and backup providers, and high and bulk paths isolated at every stage so a 50 million message campaign never delays a login code. https://media.himanshukukreja.in/lectures/problem-bank--problem-06-notification-system/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-07-news-feed News feed: push it, pull it, or both? https://media.himanshukukreja.in/lectures/problem-bank--problem-07-news-feed/poster.jpg One strong interview answer to "design a news feed": fan-out on write for ordinary authors, pull for celebrities above a follower threshold, feeds that hold only post IDs while each post object lives once, cursor pagination that stays correct while new posts arrive, a 200 ms read path, and how to survive a lost cache shard or a celebrity hot key. https://media.himanshukukreja.in/lectures/problem-bank--problem-07-news-feed/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-08-chat-system Chat: ten million open sockets, and two ticks https://media.himanshukukreja.in/lectures/problem-bank--problem-08-chat-system/poster.jpg One strong interview answer to "design a chat system": stateful WebSocket gateways in front of a stateless chat service, a per-conversation sequence number that orders every device, a sent tick only after the message is stored, client message IDs that make retries harmless, a session registry that finds Bob's gateways, catch-up by sequence, and how to restart 200 stateful servers without a reconnect storm. https://media.himanshukukreja.in/lectures/problem-bank--problem-08-chat-system/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-09-typeahead Typeahead: ten suggestions before the next keystroke https://media.himanshukukreja.in/lectures/problem-bank--problem-09-typeahead/poster.jpg One strong interview answer to "design typeahead search": two systems in one, an online path that does a single in-memory lookup from a replicated 10 GB snapshot, and an offline path that ranks queries by decayed popularity and hourly trends, filters them, and precomputes the top ten for every prefix; plus the client tricks, the CDN, and how to ship a snapshot safely. https://media.himanshukukreja.in/lectures/problem-bank--problem-09-typeahead/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-10-file-sync File sync: upload only what changed, never lose an edit https://media.himanshukukreja.in/lectures/problem-bank--problem-10-file-sync/poster.jpg One strong interview answer to "design Dropbox": files split into hashed chunks stored once in an object store, a strongly consistent metadata service that commits only after every chunk exists, a journal and cursors so any device catches up with one question, content-defined chunks for insertions, and optimistic concurrency that turns two offline edits into a conflicted copy instead of a lost one. https://media.himanshukukreja.in/lectures/problem-bank--problem-10-file-sync/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-11-distributed-cache Distributed cache: where every key lives https://media.himanshukukreja.in/lectures/problem-bank--problem-11-distributed-cache/poster.jpg One strong interview answer to "build the thing Redis Cluster is": memory sizing to 20 shards, 16,384 fixed hash slots instead of mod N, smart clients with one hop, hot-key defences from a local L1 to split keys, single flight on expiry, and what breaks on failover, split brain, races and cold restarts. https://media.himanshukukreja.in/lectures/problem-bank--problem-11-distributed-cache/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-12-pastebin Pastebin: unguessable links that vanish on time https://media.himanshukukreja.in/lectures/problem-bank--problem-12-pastebin/poster.jpg One strong interview answer to "design Pastebin": tiny traffic but terabytes of blobs, metadata in PostgreSQL and content in S3, random 8-character IDs with insert-if-absent, the CDN for immutable pastes, and expiry made exact by a read-time check, capped TTLs, a sweeper and purges. https://media.himanshukukreja.in/lectures/problem-bank--problem-12-pastebin/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-13-proximity-service Proximity service: turning near into a lookup https://media.himanshukukreja.in/lectures/problem-bank--problem-13-proximity-service/poster.jpg One strong interview answer to "show me coffee shops within 2 km": a huge stale-ok read path split from a tiny write path, a 10 GB geo index replicated rather than sharded, geohash cells with a 9-cell search that beats the boundary problem, caching by cell, and freshness by change stream plus a nightly rebuild. https://media.himanshukukreja.in/lectures/problem-bank--problem-13-proximity-service/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-14-leaderboard Leaderboard: your exact rank, live https://media.himanshukukreja.in/lectures/problem-bank--problem-14-leaderboard/poster.jpg One strong interview answer to a live game leaderboard: 5 GB that fits one node, why rank is a count that SQL can't afford and a skip-list sorted set can, packing time into scores for ties, match_id dedupe in a Lua script, sharding by player hash, exact ranks at the top and a histogram for the tail, and rebuilding derived data from Kafka and PostgreSQL. https://media.himanshukukreja.in/lectures/problem-bank--problem-14-leaderboard/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-15-metrics-monitoring Metrics monitoring: the system that must not fail https://media.himanshukukreja.in/lectures/problem-bank--problem-15-metrics-monitoring/poster.jpg One strong interview answer to a Prometheus or Datadog-style platform: 5 million points a second pushed through a gateway into Kafka, series stored as compressed chunks at about 1.5 bytes a point, a label index and tiered rollups, the cardinality trap, and an alerting path of its own with for clauses, grouping and an external watchdog. https://media.himanshukukreja.in/lectures/problem-bank--problem-15-metrics-monitoring/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-16-ad-click-aggregation Ad click aggregation: fast, and right enough to bill https://media.himanshukukreja.in/lectures/problem-bank--problem-16-ad-click-aggregation/poster.jpg One strong interview answer to counting a billion ad clicks a day: a Flink stream for minute-fresh dashboards and an hourly Spark recompute for the billed truth, exactly once as a chain from signed click_id to an overwriting sink, event-time windows with watermarks for late clicks, and salted two-stage aggregation for hot ads. https://media.himanshukukreja.in/lectures/problem-bank--problem-16-ad-click-aggregation/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-17-job-scheduler Job scheduler: on time, and harmless when twice https://media.himanshukukreja.in/lectures/problem-bank--problem-17-job-scheduler/poster.jpg One strong interview answer to cron as a service: 100 million jobs in 1,024 leased partitions, a fenced conditional claim and an outbox, a timing wheel for the next minute, look-ahead, jitter and fair queues for the top-of-the-hour spike, and an honest at-least-once guarantee made harmless by leases, attempt-number fencing, run keys and misfire policies. https://media.himanshukukreja.in/lectures/problem-bank--problem-17-job-scheduler/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-18-message-queue Message queue: opening the Kafka box https://media.himanshukukreja.in/lectures/problem-bank--problem-18-message-queue/poster.jpg One strong interview answer to a Kafka-style distributed log: a log rather than a queue so consumer groups share one copy, storage setting the broker count, segments, page cache and zero-copy for throughput, acks=all with two in-sync replicas, high watermarks and epoch-fenced leader elections, and delivery semantics set by when consumers commit. https://media.himanshukukreja.in/lectures/problem-bank--problem-18-message-queue/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-19-hotel-reservation Hotel reservations: the last room, sold once https://media.himanshukukreja.in/lectures/problem-bank--problem-19-hotel-reservation/poster.jpg One strong interview answer to hotel bookings: modest traffic on one PostgreSQL, inventory as a count per room type per night, the capacity check inside a conditional UPDATE across all nights, a unique idempotency key against double clicks, and a hold, pay, confirm saga with expiry, a sweeper and compensations for late payments. https://media.himanshukukreja.in/lectures/problem-bank--problem-19-hotel-reservation/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/problem-bank--problem-20-payment-system Payment system: never twice, never lost https://media.himanshukukreja.in/lectures/problem-bank--problem-20-payment-system/poster.jpg One strong interview answer to a marketplace payment backend: PSP tokens instead of card data, a timeout treated as unknown and resolved with the same idempotency key or a status query, one key per hop and guarded state transitions, state, ledger and outbox in one commit, a double-entry ledger in paise, and daily reconciliation with every provider. https://media.himanshukukreja.in/lectures/problem-bank--problem-20-payment-system/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-01-parking-lot Design a parking lot https://media.himanshukukreja.in/lectures/low-level-design--lld-01-parking-lot/poster.jpg The most-asked machine-coding round, run end to end: the clarifying questions that change the code, the classes and the two strategies (spot choice and pricing), the one lock that stops two gates giving one spot to two cars, the demo that proves it, and follow-ups that land as new classes. https://media.himanshukukreja.in/lectures/low-level-design--lld-01-parking-lot/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-02-lru-cache Design an LRU cache https://media.himanshukukreja.in/lectures/low-level-design--lld-02-lru-cache/poster.jpg A bounded cache where get and put are constant time: why a hash map needs a doubly linked list, sentinels, the split between the cache and a pluggable eviction policy, why even get takes the lock, the eviction callback outside it, and follow-ups from LFU to sharding. https://media.himanshukukreja.in/lectures/low-level-design--lld-02-lru-cache/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-03-rate-limiter Design a rate limiter https://media.himanshukukreja.in/lectures/low-level-design--lld-03-rate-limiter/poster.jpg The classes inside an in-process rate limiter: one interface and three algorithms chosen per rule, an injected clock, lazy token refill, the fixed window's boundary flaw, one limiter per key with its own lock, and double-checked creation so a burst of first requests never builds two buckets. https://media.himanshukukreja.in/lectures/low-level-design--lld-03-rate-limiter/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-04-elevator-system Design an elevator system https://media.himanshukukreja.in/lectures/low-level-design--lld-04-elevator-system/poster.jpg A multi-car elevator controller: hall calls and car calls, why each car runs LOOK instead of press order, stops that remember the direction wanted, a cost-based dispatch strategy, a tick-by-tick simulated morning, one lock with listeners outside it, and follow-ups that land as new strategies. https://media.himanshukukreja.in/lectures/low-level-design--lld-04-elevator-system/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-05-movie-ticket-booking Design a movie ticket booking system https://media.himanshukukreja.in/lectures/low-level-design--lld-05-movie-ticket-booking/poster.jpg Seat holds and bookings for a cinema: why check-then-book races, an all-or-nothing hold with lazy expiry behind a lock seam, the booking life cycle, a 50-thread race for two seats, a late payment that is refunded, an idempotent confirm, and the lock-ordering deadlock to avoid. https://media.himanshukukreja.in/lectures/low-level-design--lld-05-movie-ticket-booking/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-06-splitwise Design a bill-splitting app https://media.himanshukukreja.in/lectures/low-level-design--lld-06-splitwise/poster.jpg Splitwise-style expense splitting: integer paise and three split strategies that always add up, expenses as facts and balances as consequences, greedy min cash flow from six debts to three payments, a lock or a transaction per write, and a UPI settle-up recorded only once it's paid. https://media.himanshukukreja.in/lectures/low-level-design--lld-06-splitwise/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-07-vending-machine Design a vending machine https://media.himanshukukreja.in/lectures/low-level-design--lld-07-vending-machine/poster.jpg The State pattern done properly: draw the states first, one class per state answering every event, the machine as a context holding data and an escrow, change made from the coins actually in the box (where greedy fails), one lock for many inputs, and follow-ups that are new states. https://media.himanshukukreja.in/lectures/low-level-design--lld-07-vending-machine/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-08-pub-sub-logger Design a logging framework https://media.himanshukukreja.in/lectures/low-level-design--lld-08-pub-sub-logger/poster.jpg A pub-sub logging library where each pattern has a job: a chain that filters and redacts each record, a bus that fans it out by level and topic, formatters swapped per sink, an async sink that drops and counts instead of blocking, copy-on-write subscribers and isolated sinks. https://media.himanshukukreja.in/lectures/low-level-design--lld-08-pub-sub-logger/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-09-snake-and-ladder Design Snake and Ladder https://media.himanshukukreja.in/lectures/low-level-design--lld-09-snake-and-ladder/poster.jpg A favourite first machine-coding round: one Jump class for snakes and ladders, a board that rejects chains and bad squares before the first roll, dice and end-of-board rules as strategies, a turn loop with the three-sixes rule, and one lock per game so a double tap can't give a player two turns. https://media.himanshukukreja.in/lectures/low-level-design--lld-09-snake-and-ladder/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-10-chess Design a Chess Game https://media.himanshukukreja.in/lectures/low-level-design--lld-10-chess/poster.jpg Pieces know geometry, the game decides legality: make the move, look at the king, take it back. Castling rights and the en passant square as history, an undo record for every move, checkmate versus stalemate from one question, a lock even for reads, and perft counts that prove it. https://media.himanshukukreja.in/lectures/low-level-design--lld-10-chess/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-11-atm Design an ATM https://media.himanshukukreja.in/lectures/low-level-design--lld-11-atm/poster.jpg Five states with a guard on every button, a dispenser that plans notes from what is loaded (and where greedy fails), a bank with an idempotent debit and a safe reversal, and a withdrawal ordered so a jam or a lost reply always puts the money back. Plus a blocked card and a joint-account race. https://media.himanshukukreja.in/lectures/low-level-design--lld-11-atm/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-12-library-management Design a Library Management System https://media.himanshukukreja.in/lectures/low-level-design--lld-12-library-management/poster.jpg Titles versus copies: loans point at a copy, reservations at a title. A copy's life cycle with a hold shelf, a return that hands the copy to the queue in the same locked step, fines computed from dates by a pluggable policy, an inverted index for search, notifications after the lock, and a month of a small library. https://media.himanshukukreja.in/lectures/low-level-design--lld-12-library-management/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-13-hotel-reservation Design a Hotel Reservation System https://media.himanshukukreja.in/lectures/low-level-design--lld-13-hotel-reservation/poster.jpg Rooms are sold per night: half-open stays, room types counted per night with rooms assigned at check-in, 15-minute holds released lazily, pricing rules that stack per night, a lock per room type, a late payment that is refunded, and a cancellation policy. Then a 50-guest race for the last deluxe room. https://media.himanshukukreja.in/lectures/low-level-design--lld-13-hotel-reservation/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-14-ride-sharing Design a Ride-Sharing Service https://media.himanshukukreja.in/lectures/low-level-design--lld-14-ride-sharing/poster.jpg Riders, drivers, matching and fares: a grid of 1 km cells to find nearby drivers, a compare-and-set on the driver so a stale search can't double-book, a strict trip state machine, matching and fares as strategies with surge as a decorator fixed at request time, and 20 riders racing for 3 drivers. https://media.himanshukukreja.in/lectures/low-level-design--lld-14-ride-sharing/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-15-food-delivery Design a Food Delivery App https://media.himanshukukreja.in/lectures/low-level-design--lld-15-food-delivery/poster.jpg A one-restaurant cart, an idempotent checkout with a price snapshot and the charge outside the lock, an order state machine that three parties share, the nearest idle partner or a FIFO queue, refunds by stage decided in one locked step, and fifty concurrent cancels that send one refund. https://media.himanshukukreja.in/lectures/low-level-design--lld-15-food-delivery/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-16-meeting-room-scheduler Design a Meeting Room Scheduler https://media.himanshukukreja.in/lectures/low-level-design--lld-16-meeting-room-scheduler/poster.jpg Room booking with a half-open overlap test, a sorted calendar per room that finds clashes with two binary searches, a smallest-fit room strategy, recurring series booked all or nothing, invitations sent after the lock, and a 30-thread race for the boardroom. https://media.himanshukukreja.in/lectures/low-level-design--lld-16-meeting-room-scheduler/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-17-in-memory-file-system Design an In-Memory File System https://media.himanshukukreja.in/lectures/low-level-design--lld-17-in-memory-file-system/poster.jpg A file system tree built on the Composite pattern: a directory's size is its children's, paths normalised as text then walked with the error a shell would give, mkdir and mkdir -p, mv's four outcomes and its cycle check, a byte quota checked inside the lock, and one lock for the whole tree. https://media.himanshukukreja.in/lectures/low-level-design--lld-17-in-memory-file-system/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-18-text-editor-undo-redo Design a Text Editor with Undo and Redo https://media.himanshukukreja.in/lectures/low-level-design--lld-18-text-editor-undo-redo/poster.jpg Undo and redo for a text editor: edits as commands that carry their own exact inverse, two stacks with a bounded history, keystrokes grouped into word-sized steps, typing over a selection as one compound step, a new edit clearing redo, and the measured cost of snapshots instead: 5,014,950 characters against 100. https://media.himanshukukreja.in/lectures/low-level-design--lld-18-text-editor-undo-redo/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-19-online-auction Design an Online Auction https://media.himanshukukreja.in/lectures/low-level-design--lld-19-online-auction/poster.jpg Timed auctions with a five-state life cycle, tiered minimum raises, validate-then-append under a lock per auction, a clock that decides when an auction ends, a two-minute soft close with a lazy deadline heap, idempotent bid ids, events published after the lock, and a 20-thread race for a brass lamp. https://media.himanshukukreja.in/lectures/low-level-design--lld-19-online-auction/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-20-stock-exchange-order-book Design a Stock Exchange Order Book https://media.himanshukukreja.in/lectures/low-level-design--lld-20-stock-exchange-order-book/poster.jpg A limit order book for one symbol: price-time priority at the resting price, one side built from a dict of levels, a heap of prices and a FIFO per level, partial fills and an order's status, O(1) lazy cancels, every operation's cost, and one matcher thread per symbol fed by a queue, hammered by 8,000 orders from eight threads. https://media.himanshukukreja.in/lectures/low-level-design--lld-20-stock-exchange-order-book/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-21-task-scheduler-dependencies Design a Task Scheduler with Dependencies https://media.himanshukukreja.in/lectures/low-level-design--lld-21-task-scheduler-dependencies/poster.jpg A dependency-aware task scheduler: Kahn's algorithm rejects a cycle at submit and, as counts of unmet dependencies, releases tasks live; a ready heap by priority and a delayed heap by time behind one condition variable; tasks run outside the lock; doubling backoff for a flaky test; cancels and failures that skip everything downstream; fixed-rate recurring tasks; and 40 tasks on 4 workers. https://media.himanshukukreja.in/lectures/low-level-design--lld-21-task-scheduler-dependencies/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/low-level-design--lld-22-key-value-store-ttl-transactions Design a Key-Value Store with TTL and Transactions https://media.himanshukukreja.in/lectures/low-level-design--lld-22-key-value-store-ttl-transactions/poster.jpg An in-memory key-value store: committed data in a locked store and uncommitted writes in each session's stack of transaction layers, versions validated at the outermost commit, lazy expiry on read plus bounded sweeps from a heap of deadlines, eviction behind an interface, and 4,000 increments from eight threads with none lost. https://media.himanshukukreja.in/lectures/low-level-design--lld-22-key-value-store-ttl-transactions/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--distributed-transactions-2pc-saga-pattern WonderTravel: when two-phase commit met Black Friday https://media.himanshukukreja.in/lectures/case-files--distributed-transactions-2pc-saga-pattern/poster.jpg How WonderTravel's one-click flight, hotel and car booking, built on two-phase commit, locked thousands of bookings when its coordinator crashed and split a booking in a network partition, and how a saga of local commits, compensating actions and idempotent retries replaced it. https://media.himanshukukreja.in/lectures/case-files--distributed-transactions-2pc-saga-pattern/video.mp4 720 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--websockets-vs-webrtc-video-communication ConnectNow: the night video ran over WebSockets https://media.himanshukukreja.in/lectures/case-files--websockets-vs-webrtc-video-communication/poster.jpg How ConnectNow's video calls, relayed frame by frame through a WebSocket server, fell apart before an investor demo, and how a hybrid design fixed it: WebSockets for signalling and chat, WebRTC for media, STUN and TURN for NAT, and SFUs once calls grow. https://media.himanshukukreja.in/lectures/case-files--websockets-vs-webrtc-video-communication/video.mp4 660 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--leader-follower-replication-node-outages When the database leader goes dark https://media.himanshukukreja.in/lectures/case-files--leader-follower-replication-node-outages/poster.jpg The StreamFlix scenario: what happens when a follower or the leader of a replicated database fails, the failover dance, synchronous vs asynchronous replication by what the data is worth, how PostgreSQL and MongoDB fail over, and the split brain GitHub hit in 2018. https://media.himanshukukreja.in/lectures/case-files--leader-follower-replication-node-outages/video.mp4 660 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--cdn-cache-poisoning-disaster CDN cache poisoning: someone else's cart https://media.himanshukukreja.in/lectures/case-files--cdn-cache-poisoning-disaster/poster.jpg The ShopFast case file: on Black Friday a CDN rule cached /api/* by URL path alone and ignored the origin's private headers, so one user's cart, address and card digits reached others while every backend dashboard stayed green. How it was found, contained and fixed for good. https://media.himanshukukreja.in/lectures/case-files--cdn-cache-poisoning-disaster/video.mp4 660 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--integer-overflow-auto-increment-crisis The 2 AM integer overflow https://media.himanshukukreja.in/lectures/case-files--integer-overflow-auto-increment-crisis/poster.jpg An event log's 32-bit auto-increment ID reaches 2,147,483,647 after about 18 months at 4 million events a day, and inserts fail silently. Why it stays quiet, the emergency fixes and how to choose, UUID and Snowflake IDs, and how to see the ceiling coming. https://media.himanshukukreja.in/lectures/case-files--integer-overflow-auto-increment-crisis/video.mp4 660 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--digipin-scalable-location-service DIGIPIN: an address for every 4-metre square https://media.himanshukukreja.in/lectures/case-files--digipin-scalable-location-service/poster.jpg A case study that designs a GeoHash-based location service around DIGIPIN's goal: a 10-character code for every small square of India, worked out from latitude and longitude, served through edge and Redis caches, PostGIS partitioned by state, and three regions that survive a lost database. https://media.himanshukukreja.in/lectures/case-files--digipin-scalable-location-service/video.mp4 720 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--scalable-spam-detection-bloom-filter GlobalForum: catching 1.2 billion bad links in 2 GB https://media.himanshukukreja.in/lectures/case-files--scalable-spam-detection-bloom-filter/poster.jpg How GlobalForum's database-backed spam check collapsed in a 10x traffic spike, and how a Bloom filter, about 2 GB of bits in Redis with no false negatives, answers most link checks without touching the database, stays current through rebuilds, and holds up in an attack. https://media.himanshukukreja.in/lectures/case-files--scalable-spam-detection-bloom-filter/video.mp4 720 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--ios-bridge-cross-platform-streaming iOS Bridge: the simulator on every developer's screen https://media.himanshukukreja.in/lectures/case-files--ios-bridge-cross-platform-streaming/poster.jpg How I built iOS Bridge, an open-source tool that streams iOS simulators from one Mac to Windows, Linux or a browser: from a choppy screenshot loop to newest-frame-wins WebRTC, click-to-tap mapping, and sessions that survive a server restart. https://media.himanshukukreja.in/lectures/case-files--ios-bridge-cross-platform-streaming/video.mp4 840 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--bridgelink-remote-android-testing BridgeLink: the phones are on a desk, the developers aren't https://media.himanshukukreja.in/lectures/case-files--bridgelink-remote-android-testing/poster.jpg How I turned plain adb and a bore tunnel into BridgeLink, an open-source CLI that makes the Android phones a team already owns reachable from anywhere: a tunnel manager, three-step WiFi, health checks that catch hung devices, and auto-activation that brings a phone back in about two seconds. https://media.himanshukukreja.in/lectures/case-files--bridgelink-remote-android-testing/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--irctc-tatkal-500-seats-2-million-users IRCTC Tatkal: 500 seats, 2 million people https://media.himanshukukreja.in/lectures/case-files--irctc-tatkal-500-seats-2-million-users/poster.jpg How a Tatkal rush sells a few hundred seats to about two million people in ten seconds without a double booking: a cheap counter at the door, a waiting room that breathes with the database, hold-then-confirm with automatic refunds, layered bot defences, and why looking and buying must not share servers. https://media.himanshukukreja.in/lectures/case-files--irctc-tatkal-500-seats-2-million-users/video.mp4 720 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--crowdstrike-one-file-8-million-blue-screens CrowdStrike: one file, 8.5 million blue screens https://media.himanshukukreja.in/lectures/case-files--crowdstrike-one-file-8-million-blue-screens/poster.jpg How a 78-minute configuration update, Channel File 291, crashed about 8.5 million Windows machines on 19 July 2024: a 21-field rule against a 20-input sensor in kernel code, a validator that trusted the wrong file, no staged rollout, and machines that couldn't stay up long enough to be fixed. https://media.himanshukukreja.in/lectures/case-files--crowdstrike-one-file-8-million-blue-screens/video.mp4 900 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/case-files--hotstar-25-million-viewers-one-match Hotstar: 25.3 million viewers, one match https://media.himanshukukreja.in/lectures/case-files--hotstar-25-million-viewers-one-match/poster.jpg How Hotstar served 25.3 million people watching India vs New Zealand at once on 10 July 2019: why reactive autoscaling was too late, the capacity ladder and the scorecard as a forecast, a CDN built as a shock absorber, panic mode, and the thundering herd when the wicket falls. https://media.himanshukukreja.in/lectures/case-files--hotstar-25-million-viewers-one-match/video.mp4 960 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--37signals-leaves-the-cloud Leaving the cloud: $3.2 million down to $1.3 million https://media.himanshukukreja.in/lectures/war-stories--37signals-leaves-the-cloud/poster.jpg How 37signals, the makers of Basecamp and HEY, bought about $700,000 of servers, moved seven apps off AWS and cut its yearly cloud bill from $3.2 million to $1.3 million. https://media.himanshukukreja.in/lectures/war-stories--37signals-leaves-the-cloud/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--github-43-second-partition 43 seconds that cost GitHub a day https://media.himanshukukreja.in/lectures/war-stories--github-43-second-partition/poster.jpg How a 43-second network cut on 21 October 2018 let GitHub's databases fail over across the country, leaving two incomplete copies and 24 hours and 11 minutes of degraded service. https://media.himanshukukreja.in/lectures/war-stories--github-43-second-partition/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--s3-bucket-name-clash-bill The empty test bucket with a $1,300 bill https://media.himanshukukreja.in/lectures/war-stories--s3-bucket-name-clash-bill/poster.jpg A developer's new S3 test bucket shared its name with an open-source tool's placeholder, strangers' machines sent it nearly 100 million requests, and he got the bill. https://media.himanshukukreja.in/lectures/war-stories--s3-bucket-name-clash-bill/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--atlassian-775-customers-deleted The cleanup script that deleted 883 Atlassian sites https://media.himanshukukreja.in/lectures/war-stories--atlassian-775-customers-deleted/poster.jpg How a script meant to remove one old app was handed whole-site IDs on 5 April 2022, deleted 883 sites belonging to 775 customers in 23 minutes, and left some without access for up to 14 days. https://media.himanshukukreja.in/lectures/war-stories--atlassian-775-customers-deleted/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--netflix-seven-years-to-the-cloud Netflix's seven years to the cloud https://media.himanshukukreja.in/lectures/war-stories--netflix-seven-years-to-the-cloud/poster.jpg A 2008 database corruption stopped Netflix shipping DVDs for three days, and its answer was a seven-year rebuild of almost all its technology for the cloud. https://media.himanshukukreja.in/lectures/war-stories--netflix-seven-years-to-the-cloud/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--prime-video-monitoring-monolith The Prime Video tool that got cheaper as a monolith https://media.himanshukukreja.in/lectures/war-stories--prime-video-monitoring-monolith/poster.jpg A Prime Video monitoring tool built from serverless pieces hit a hard limit at about 5% of its load; folded into one process, it cost over 90% less. https://media.himanshukukreja.in/lectures/war-stories--prime-video-monitoring-monolith/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--gitlab-database-deletion GitLab wiped its main database, and the backups weren't there https://media.himanshukukreja.in/lectures/war-stories--gitlab-database-deletion/poster.jpg How a GitLab engineer wiped the primary database thinking it was the copy on 31 January 2017, found every backup method missing, and was saved by a snapshot taken for load testing. https://media.himanshukukreja.in/lectures/war-stories--gitlab-database-deletion/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--cowin-registration-opening-day CoWIN: 383 million hits, no slots to give https://media.himanshukukreja.in/lectures/war-stories--cowin-registration-opening-day/poster.jpg How CoWIN took 383 million API hits in three hours when vaccine registration opened to everyone aged 18 to 44 on 28 April 2021, and why most people still couldn't book a slot. https://media.himanshukukreja.in/lectures/war-stories--cowin-registration-opening-day/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--discord-trillions-of-messages Discord moved trillions of messages in nine days https://media.himanshukukreja.in/lectures/war-stories--discord-trillions-of-messages/poster.jpg How Discord planned for years, put a Rust layer in front of its database, then copied trillions of messages from Cassandra to ScyllaDB in nine days. https://media.himanshukukreja.in/lectures/war-stories--discord-trillions-of-messages/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--dropbox-magic-pocket Dropbox's BASE Jump: 500 petabytes off the cloud https://media.himanshukukreja.in/lectures/war-stories--dropbox-magic-pocket/poster.jpg How Dropbox built Magic Pocket, ran it dark, then moved 90 percent of its users' files out of Amazon S3 and onto its own machines in a six-month sprint. https://media.himanshukukreja.in/lectures/war-stories--dropbox-magic-pocket/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--flipkart-big-billion-day-apology Flipkart's Big Billion Day, and the apology https://media.himanshukukreja.in/lectures/war-stories--flipkart-big-billion-day-apology/poster.jpg How Flipkart prepared nearly 5,000 servers for 20 times the traffic growth, still fell over on its 6 October 2014 sale, and how its founders said sorry the next day. https://media.himanshukukreja.in/lectures/war-stories--flipkart-big-billion-day-apology/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--google-flagged-the-whole-web One slash flagged the whole web https://media.himanshukukreja.in/lectures/war-stories--google-flagged-the-whole-web/poster.jpg How a single '/' checked into Google's list of harmful sites matched every URL and put a malware warning on each and every search result for about 40 minutes on 31 January 2009. https://media.himanshukukreja.in/lectures/war-stories--google-flagged-the-whole-web/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--google-lightning-belgium Four lightning strikes, one data center https://media.himanshukukreja.in/lectures/war-stories--google-lightning-belgium/poster.jpg In August 2015 lightning hit the grid near Google's Belgian data center four times in a row, and a sliver of just-written customer data was lost for good. https://media.himanshukukreja.in/lectures/war-stories--google-lightning-belgium/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--nse-trading-halt-2021 The day NSE stopped trading for four hours https://media.himanshukukreja.in/lectures/war-stories--nse-trading-halt-2021/poster.jpg On 24 February 2021 NSE's trading engine was fine, but its risk system lost its telecom links, and India's largest exchange halted for about four hours. https://media.himanshukukreja.in/lectures/war-stories--nse-trading-halt-2021/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--swiggy-new-years-eve-war-room Inside Swiggy's New Year's Eve war room https://media.himanshukukreja.in/lectures/war-stories--swiggy-new-years-eve-war-room/poster.jpg How Swiggy prepared for its busiest night of 2022, weeks of forecasting and scaling, 400 people in one office, and what still broke anyway. https://media.himanshukukreja.in/lectures/war-stories--swiggy-new-years-eve-war-room/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--jiocinema-ipl-2023-record Free IPL, 3.21 crore at once https://media.himanshukukreja.in/lectures/war-stories--jiocinema-ipl-2023-record/poster.jpg How JioCinema made the 2023 IPL free to watch, and how the peak climbed from 1.6 crore at the opener to a reported world-record 3.21 crore concurrent viewers at the final. https://media.himanshukukreja.in/lectures/war-stories--jiocinema-ipl-2023-record/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--knight-capital-45-minutes Knight Capital: $460 million in 45 minutes https://media.himanshukukreja.in/lectures/war-stories--knight-capital-45-minutes/poster.jpg How one server that missed a deploy, and a reused flag, woke up retired trading code at Knight Capital on 1 August 2012 and lost over $460 million in about 45 minutes. https://media.himanshukukreja.in/lectures/war-stories--knight-capital-45-minutes/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--mars-climate-orbiter-units The Mars orbiter lost to the wrong units https://media.himanshukukreja.in/lectures/war-stories--mars-climate-orbiter-units/poster.jpg One ground program wrote pound-seconds, the navigation software read newton-seconds, and after a 9-month cruise Mars Climate Orbiter arrived about 170 km too low. https://media.himanshukukreja.in/lectures/war-stories--mars-climate-orbiter-units/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--fastly-one-customer-config One valid setting broke 85% of Fastly's network https://media.himanshukukreja.in/lectures/war-stories--fastly-one-customer-config/poster.jpg How a bug that shipped on 12 May 2021 sat quiet for almost four weeks until one customer's valid configuration change set it off and 85 percent of Fastly's network returned errors. https://media.himanshukukreja.in/lectures/war-stories--fastly-one-customer-config/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--leap-second-2012 The extra second that jammed Linux https://media.himanshukukreja.in/lectures/war-stories--leap-second-2012/poster.jpg How the leap second added at midnight GMT on 30 June 2012 made Linux timers fire early or at once, spun CPUs at Reddit, Gawker and Mozilla, and why code that almost never runs is the riskiest code you have. https://media.himanshukukreja.in/lectures/war-stories--leap-second-2012/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--cloudflare-one-regex One regex took Cloudflare offline https://media.himanshukukreja.in/lectures/war-stories--cloudflare-one-regex/poster.jpg How a new firewall rule in simulate mode hit catastrophic backtracking, maxed out the CPUs serving web traffic across Cloudflare's whole network and caused 27 minutes of outage on 2 July 2019. https://media.himanshukukreja.in/lectures/war-stories--cloudflare-one-regex/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--facebook-bgp-six-hours One command took Facebook off the internet https://media.himanshukukreja.in/lectures/war-stories--facebook-bgp-six-hours/poster.jpg How a routine maintenance command on 4 October 2021 cut off every Facebook data center, made its DNS servers vanish from the internet, and locked engineers out of their own tools for nearly six hours. https://media.himanshukukreja.in/lectures/war-stories--facebook-bgp-six-hours/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--aws-s3-one-wrong-input One wrong input took down S3 https://media.himanshukukreja.in/lectures/war-stories--aws-s3-one-wrong-input/poster.jpg How one mistyped input in a routine command removed far too many servers and kept Amazon S3 in Northern Virginia down for about four hours in February 2017. https://media.himanshukukreja.in/lectures/war-stories--aws-s3-one-wrong-input/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--pokemon-go-fifty-times-the-estimate Pokémon GO: 50 times the plan https://media.himanshukukreja.in/lectures/war-stories--pokemon-go-fifty-times-the-estimate/poster.jpg Niantic and Google planned for a worst case of 5x their traffic target; Pokémon GO's launch brought 50x, and they rebuilt the platform while it was live. https://media.himanshukukreja.in/lectures/war-stories--pokemon-go-fifty-times-the-estimate/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--roblox-73-hour-outage Roblox's 73 hours in the dark https://media.himanshukukreja.in/lectures/war-stories--roblox-73-hour-outage/poster.jpg In October 2021 Roblox was down for 73 hours because Consul, the service directory everything depended on, choked on two stacked problems. https://media.himanshukukreja.in/lectures/war-stories--roblox-73-hour-outage/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--segment-back-to-monolith 140 microservices, back to one https://media.himanshukukreja.in/lectures/war-stories--segment-back-to-monolith/poster.jpg Why Segment split its pipeline into one service and queue per destination, how that grew into over 140 services that kept 3 full-time engineers busy, and what it gained and gave up by merging them back into one. https://media.himanshukukreja.in/lectures/war-stories--segment-back-to-monolith/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--slack-january-2021-scale-up Slack's first workday of 2021 https://media.himanshukukreja.in/lectures/war-stories--slack-january-2021-scale-up/poster.jpg How the jump from the quietest week of the year to one of the busiest overloaded a self-scaling network hub on 4 January 2021, took Slack's dashboards down and stalled its own scale-up. https://media.himanshukukreja.in/lectures/war-stories--slack-january-2021-scale-up/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--whatsapp-two-million-connections 2 million connections, one server https://media.himanshukukreja.in/lectures/war-stories--whatsapp-two-million-connections/poster.jpg How one WhatsApp server held 2,277,845 open connections in January 2012 with CPU to spare, and how, two years later, 32 engineers were behind a service with over 450 million monthly users. https://media.himanshukukreja.in/lectures/war-stories--whatsapp-two-million-connections/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--azure-leap-day-certificate Azure tripped over 29 February https://media.himanshukukreja.in/lectures/war-stories--azure-leap-day-certificate/poster.jpg How adding 1 to the year on 29 February 2012 broke certificate creation on Windows Azure, and how its own self-healing spread the bug from server to server. https://media.himanshukukreja.in/lectures/war-stories--azure-leap-day-certificate/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/lectures/war-stories--zoom-participants-not-users Zoom's 300 million: participants, not users https://media.himanshukukreja.in/lectures/war-stories--zoom-participants-not-users/poster.jpg Zoom really did grow from 10 million to 300 million daily meeting participants in 2020, but that number counted meetings joined, not people. https://media.himanshukukreja.in/lectures/war-stories--zoom-participants-not-users/video.mp4 180 yes monthly 0.6 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-01-indian-upi-system--deemed-success Your bank took the money. Then the other bank timed out. https://media.himanshukukreja.in/lectures/shorts--bonus-01-indian-upi-system--deemed-success/poster.jpg?v=3f2942a1ed3d Side quest 1 · UPI: Your bank took the money. Then the other bank timed out. https://media.himanshukukreja.in/lectures/shorts--bonus-01-indian-upi-system--deemed-success/video.mp4?v=3f2942a1ed3d 103 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-01-indian-upi-system--never-holds-money UPI routes 800 million payments a day and never holds a rupee https://media.himanshukukreja.in/lectures/shorts--bonus-01-indian-upi-system--never-holds-money/poster.jpg?v=97727da9fc6f Side quest 1 · UPI: UPI routes 800 million payments a day and never holds a rupee https://media.himanshukukreja.in/lectures/shorts--bonus-01-indian-upi-system--never-holds-money/video.mp4?v=97727da9fc6f 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-01-indian-upi-system--status-check-flood Status checks, not payments, took UPI down https://media.himanshukukreja.in/lectures/shorts--bonus-01-indian-upi-system--status-check-flood/poster.jpg?v=20d04e33bee6 Side quest 1 · UPI: Status checks, not payments, took UPI down https://media.himanshukukreja.in/lectures/shorts--bonus-01-indian-upi-system--status-check-flood/video.mp4?v=20d04e33bee6 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-02-whatsapp-messaging--delete-on-ack WhatsApp forgets your messages. On purpose. https://media.himanshukukreja.in/lectures/shorts--bonus-02-whatsapp-messaging--delete-on-ack/poster.jpg?v=f168047ad88a Side quest 2 · WhatsApp: WhatsApp forgets your messages. On purpose. https://media.himanshukukreja.in/lectures/shorts--bonus-02-whatsapp-messaging--delete-on-ack/video.mp4?v=f168047ad88a 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-02-whatsapp-messaging--dropped-sync 40 messages, and the connection drops halfway https://media.himanshukukreja.in/lectures/shorts--bonus-02-whatsapp-messaging--dropped-sync/poster.jpg?v=9f034e28468b Side quest 2 · WhatsApp: 40 messages, and the connection drops halfway https://media.himanshukukreja.in/lectures/shorts--bonus-02-whatsapp-messaging--dropped-sync/video.mp4?v=9f034e28468b 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-02-whatsapp-messaging--presence-storm Typing indicators are ten times your messages https://media.himanshukukreja.in/lectures/shorts--bonus-02-whatsapp-messaging--presence-storm/poster.jpg?v=1ac6a0c3ae0e Side quest 2 · WhatsApp: Typing indicators are ten times your messages https://media.himanshukukreja.in/lectures/shorts--bonus-02-whatsapp-messaging--presence-storm/video.mp4?v=1ac6a0c3ae0e 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-03-aadhar-identity-system--fraudster-picks-demographics The shortcut that shrinks Aadhaar's search 72,000 times, and why it fails https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--fraudster-picks-demographics/poster.jpg?v=67705acfe53c Side quest 3 · Aadhaar: The shortcut that shrinks Aadhaar's search 72,000 times, and why it fails https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--fraudster-picks-demographics/video.mp4?v=67705acfe53c 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-03-aadhar-identity-system--lookup-vs-search 200 milliseconds to check you. 3,170 years to prove you're new. https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--lookup-vs-search/poster.jpg?v=d43cba9a4435 Side quest 3 · Aadhaar: 200 milliseconds to check you. 3,170 years to prove you're new. https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--lookup-vs-search/video.mp4?v=d43cba9a4435 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-03-aadhar-identity-system--never-lower-the-bar A worn thumb fails at the ration shop. Lower the threshold? https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--never-lower-the-bar/poster.jpg?v=85a8c81d3e66 Side quest 3 · Aadhaar: A worn thumb fails at the ration shop. Lower the threshold? https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--never-lower-the-bar/video.mp4?v=85a8c81d3e66 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-03-aadhar-identity-system--return-a-bit Why Aadhaar tells a bank only yes or no https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--return-a-bit/poster.jpg?v=94072f8eb643 Side quest 3 · Aadhaar: Why Aadhaar tells a bank only yes or no https://media.himanshukukreja.in/lectures/shorts--bonus-03-aadhar-identity-system--return-a-bit/video.mp4?v=94072f8eb643 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-04-visa-mastercard-payments--approval-is-a-promise Your card was approved. Not a cent has moved. https://media.himanshukukreja.in/lectures/shorts--bonus-04-visa-mastercard-payments--approval-is-a-promise/poster.jpg?v=6116c4059dae Side quest 4 · Visa and Mastercard: Your card was approved. Not a cent has moved. https://media.himanshukukreja.in/lectures/shorts--bonus-04-visa-mastercard-payments--approval-is-a-promise/video.mp4?v=6116c4059dae 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-04-visa-mastercard-payments--card-testing-bot 20,000 stolen-card guesses a minute, invisible to every merchant https://media.himanshukukreja.in/lectures/shorts--bonus-04-visa-mastercard-payments--card-testing-bot/poster.jpg?v=6195f5fd4a1b Side quest 4 · Visa and Mastercard: 20,000 stolen-card guesses a minute, invisible to every merchant https://media.himanshukukreja.in/lectures/shorts--bonus-04-visa-mastercard-payments--card-testing-bot/video.mp4?v=6195f5fd4a1b 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-04-visa-mastercard-payments--stand-in Black Friday. The bank stops answering. 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The pages that matter are 5 minutes old. https://media.himanshukukreja.in/lectures/shorts--bonus-05-google-search--fresh-tier/video.mp4?v=f7c956cf9379 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-05-google-search--shard-by-document Google sends every query to every shard, on purpose https://media.himanshukukreja.in/lectures/shorts--bonus-05-google-search--shard-by-document/poster.jpg?v=e2bec65724ba Side quest 5 · Google Search: Google sends every query to every shard, on purpose https://media.himanshukukreja.in/lectures/shorts--bonus-05-google-search--shard-by-document/video.mp4?v=e2bec65724ba 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-05-google-search--tail-is-the-median Every Google search hits a slow machine. Almost every time. https://media.himanshukukreja.in/lectures/shorts--bonus-05-google-search--tail-is-the-median/poster.jpg?v=21b4ad44d71b Side quest 5 · Google Search: Every Google search hits a slow machine. 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You keep watching. https://media.himanshukukreja.in/lectures/shorts--bonus-06-netflix-streaming--plan-b-in-the-manifest/poster.jpg?v=c9613e068b6a Side quest 6 · Netflix: The box streaming your show dies mid-episode. You keep watching. https://media.himanshukukreja.in/lectures/shorts--bonus-06-netflix-streaming--plan-b-in-the-manifest/video.mp4?v=c9613e068b6a 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-07-spotify-streaming--count-each-play-once 30 songs on a flight: how Spotify pays for each play exactly once https://media.himanshukukreja.in/lectures/shorts--bonus-07-spotify-streaming--count-each-play-once/poster.jpg?v=d089a555b16c Side quest 7 · Spotify: 30 songs on a flight: how Spotify pays for each play exactly once https://media.himanshukukreja.in/lectures/shorts--bonus-07-spotify-streaming--count-each-play-once/video.mp4?v=d089a555b16c 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-07-spotify-streaming--fastest-fetch-is-no-fetch Most Spotify taps never touch the network https://media.himanshukukreja.in/lectures/shorts--bonus-07-spotify-streaming--fastest-fetch-is-no-fetch/poster.jpg?v=6975987d40db Side quest 7 · Spotify: Most Spotify taps never touch the network https://media.himanshukukreja.in/lectures/shorts--bonus-07-spotify-streaming--fastest-fetch-is-no-fetch/video.mp4?v=6975987d40db 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-07-spotify-streaming--zero-plays How Spotify recommends a song nobody has played yet https://media.himanshukukreja.in/lectures/shorts--bonus-07-spotify-streaming--zero-plays/poster.jpg?v=0ec72431d7bf Side quest 7 · Spotify: How Spotify recommends a song nobody has played yet https://media.himanshukukreja.in/lectures/shorts--bonus-07-spotify-streaming--zero-plays/video.mp4?v=0ec72431d7bf 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-08-AWS-S3--erasure-coding S3 survives losing a whole zone, without three copies https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--erasure-coding/poster.jpg?v=7fed3b4303b0 Side quest 8 · AWS S3: S3 survives losing a whole zone, without three copies https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--erasure-coding/video.mp4?v=7fed3b4303b0 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-08-AWS-S3--put-then-404 S3 said 200 OK. Then the read said 404. https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--put-then-404/poster.jpg?v=4e6c47fe2071 Side quest 8 · AWS S3: S3 said 200 OK. Then the read said 404. https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--put-then-404/video.mp4?v=4e6c47fe2071 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-08-AWS-S3--slow-down-means-wait S3 answers 503 Slow Down. Retrying harder makes it worse. https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--slow-down-means-wait/poster.jpg?v=d58a561fb45b Side quest 8 · AWS S3: S3 answers 503 Slow Down. Retrying harder makes it worse. https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--slow-down-means-wait/video.mp4?v=d58a561fb45b 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-08-AWS-S3--stolen-keys 11 nines of durability can't save you from one valid DELETE https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--stolen-keys/poster.jpg?v=c0dcbf317112 Side quest 8 · AWS S3: 11 nines of durability can't save you from one valid DELETE https://media.himanshukukreja.in/lectures/shorts--bonus-08-AWS-S3--stolen-keys/video.mp4?v=c0dcbf317112 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-09-uber--hexagon-cells Why Uber chops the map into hexagons https://media.himanshukukreja.in/lectures/shorts--bonus-09-uber--hexagon-cells/poster.jpg?v=b9c4b5bf9c2f Side quest 9 · Uber: Why Uber chops the map into hexagons https://media.himanshukukreja.in/lectures/shorts--bonus-09-uber--hexagon-cells/video.mp4?v=b9c4b5bf9c2f 100 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-09-uber--nearest-isnt-best Why Uber doesn't just send the nearest car https://media.himanshukukreja.in/lectures/shorts--bonus-09-uber--nearest-isnt-best/poster.jpg?v=c36000dbe636 Side quest 9 · Uber: Why Uber doesn't just send the nearest car https://media.himanshukukreja.in/lectures/shorts--bonus-09-uber--nearest-isnt-best/video.mp4?v=c36000dbe636 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-09-uber--region-failover A region dies with 200,000 trips in progress https://media.himanshukukreja.in/lectures/shorts--bonus-09-uber--region-failover/poster.jpg?v=11da1e87f89c Side quest 9 · Uber: A region dies with 200,000 trips in progress https://media.himanshukukreja.in/lectures/shorts--bonus-09-uber--region-failover/video.mp4?v=11da1e87f89c 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-10-twitter-x--cache-ids-not-tweets 250 million timelines in memory: cache IDs, not tweets https://media.himanshukukreja.in/lectures/shorts--bonus-10-twitter-x--cache-ids-not-tweets/poster.jpg?v=ca8d204674ba Side quest 10 · Twitter/X: 250 million timelines in memory: cache IDs, not tweets https://media.himanshukukreja.in/lectures/shorts--bonus-10-twitter-x--cache-ids-not-tweets/video.mp4?v=ca8d204674ba 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-10-twitter-x--degrade-by-delay Super Bowl: let the timeline run late https://media.himanshukukreja.in/lectures/shorts--bonus-10-twitter-x--degrade-by-delay/poster.jpg?v=f759b7549054 Side quest 10 · Twitter/X: Super Bowl: let the timeline run late https://media.himanshukukreja.in/lectures/shorts--bonus-10-twitter-x--degrade-by-delay/video.mp4?v=f759b7549054 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-10-twitter-x--tombstone-delete Deleting a post that's already in every timeline https://media.himanshukukreja.in/lectures/shorts--bonus-10-twitter-x--tombstone-delete/poster.jpg?v=bbc207ea1982 Side quest 10 · Twitter/X: Deleting a post that's already in every timeline https://media.himanshukukreja.in/lectures/shorts--bonus-10-twitter-x--tombstone-delete/video.mp4?v=bbc207ea1982 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-11-irctc-booking-system--deemed-pending The payment timed out. Did you pay? https://media.himanshukukreja.in/lectures/shorts--bonus-11-irctc-booking-system--deemed-pending/poster.jpg?v=31c5c1d5a76b Side quest 11 · IRCTC: The payment timed out. Did you pay? https://media.himanshukukreja.in/lectures/shorts--bonus-11-irctc-booking-system--deemed-pending/video.mp4?v=31c5c1d5a76b 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-11-irctc-booking-system--dumb-counter 500 Tatkal seats, 2 million people: it's not a database problem https://media.himanshukukreja.in/lectures/shorts--bonus-11-irctc-booking-system--dumb-counter/poster.jpg?v=879c936a1c3a Side quest 11 · IRCTC: 500 Tatkal seats, 2 million people: it's not a database problem https://media.himanshukukreja.in/lectures/shorts--bonus-11-irctc-booking-system--dumb-counter/video.mp4?v=879c936a1c3a 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-11-irctc-booking-system--fair-not-fastest Why Tatkal's queue isn't first come, first served https://media.himanshukukreja.in/lectures/shorts--bonus-11-irctc-booking-system--fair-not-fastest/poster.jpg?v=faee3d200a63 Side quest 11 · IRCTC: Why Tatkal's queue isn't first come, first served https://media.himanshukukreja.in/lectures/shorts--bonus-11-irctc-booking-system--fair-not-fastest/video.mp4?v=faee3d200a63 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-12-blinkit-quick-commerce--close-at-15-open-at-8 This dark store closes at 15 minutes of backlog, and reopens only under 8 https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--close-at-15-open-at-8/poster.jpg?v=d68e87d1d02c Side quest 12 · Blinkit: This dark store closes at 15 minutes of backlog, and reopens only under 8 https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--close-at-15-open-at-8/video.mp4?v=d68e87d1d02c 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-12-blinkit-quick-commerce--far-order-first Why the dark store packs the far order first https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--far-order-first/poster.jpg?v=e7bb37a73b54 Side quest 12 · Blinkit: Why the dark store packs the far order first https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--far-order-first/video.mp4?v=e7bb37a73b54 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-12-blinkit-quick-commerce--rain-on-match-night Cricket final, heavy rain: who does the dark store say no to? https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--rain-on-match-night/poster.jpg?v=4904ec4c0d25 Side quest 12 · Blinkit: Cricket final, heavy rain: who does the dark store say no to? https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--rain-on-match-night/video.mp4?v=4904ec4c0d25 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-12-blinkit-quick-commerce--ten-minute-math Where Blinkit's ten minutes really come from https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--ten-minute-math/poster.jpg?v=25fa5b4c0b13 Side quest 12 · Blinkit: Where Blinkit's ten minutes really come from https://media.himanshukukreja.in/lectures/shorts--bonus-12-blinkit-quick-commerce--ten-minute-math/video.mp4?v=25fa5b4c0b13 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-13-zerodha-kite-trading--binary-price-snapshots Live prices to 1.5 million screens: binary, latest only https://media.himanshukukreja.in/lectures/shorts--bonus-13-zerodha-kite-trading--binary-price-snapshots/poster.jpg?v=677a77b90eb4 Side quest 13 · Zerodha Kite: Live prices to 1.5 million screens: binary, latest only https://media.himanshukukreja.in/lectures/shorts--bonus-13-zerodha-kite-trading--binary-price-snapshots/video.mp4?v=677a77b90eb4 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-13-zerodha-kite-trading--budget-day-ceiling Budget day: when the exchange becomes your bottleneck https://media.himanshukukreja.in/lectures/shorts--bonus-13-zerodha-kite-trading--budget-day-ceiling/poster.jpg?v=8dda178610a8 Side quest 13 · Zerodha Kite: Budget day: when the exchange becomes your bottleneck https://media.himanshukukreja.in/lectures/shorts--bonus-13-zerodha-kite-trading--budget-day-ceiling/video.mp4?v=8dda178610a8 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-13-zerodha-kite-trading--unknown-not-failed Your order went out. Then the line dropped. https://media.himanshukukreja.in/lectures/shorts--bonus-13-zerodha-kite-trading--unknown-not-failed/poster.jpg?v=ce1870c370b0 Side quest 13 · Zerodha Kite: Your order went out. Then the line dropped. https://media.himanshukukreja.in/lectures/shorts--bonus-13-zerodha-kite-trading--unknown-not-failed/video.mp4?v=ce1870c370b0 93 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-14-chatgpt-llm-serving--batch-every-step Seven replies finish. Their GPU seats sit empty. https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--batch-every-step/poster.jpg?v=b529128322c4 Side quest 14 · ChatGPT: Seven replies finish. Their GPU seats sit empty. https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--batch-every-step/video.mp4?v=b529128322c4 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-14-chatgpt-llm-serving--gpus-are-melting "Our GPUs are melting": who gets an image on launch day? https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--gpus-are-melting/poster.jpg?v=ff4823623e5d Side quest 14 · ChatGPT: "Our GPUs are melting": who gets an image on launch day? https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--gpus-are-melting/video.mp4?v=ff4823623e5d 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-14-chatgpt-llm-serving--never-pay-twice Your Wi-Fi drops mid-reply. The GPU never notices. https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--never-pay-twice/poster.jpg?v=69d782373b69 Side quest 14 · ChatGPT: Your Wi-Fi drops mid-reply. The GPU never notices. https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--never-pay-twice/video.mp4?v=69d782373b69 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-14-chatgpt-llm-serving--share-the-gpu Why one chat reply shares a GPU with 224 others https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--share-the-gpu/poster.jpg?v=e95ff79d819c Side quest 14 · ChatGPT: Why one chat reply shares a GPU with 224 others https://media.himanshukukreja.in/lectures/shorts--bonus-14-chatgpt-llm-serving--share-the-gpu/video.mp4?v=e95ff79d819c 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-15-figma-multiplayer--fenced-owner The server holding your Figma file dies mid-review https://media.himanshukukreja.in/lectures/shorts--bonus-15-figma-multiplayer--fenced-owner/poster.jpg?v=5600620863c8 Side quest 15 · Figma: The server holding your Figma file dies mid-review https://media.himanshukukreja.in/lectures/shorts--bonus-15-figma-multiplayer--fenced-owner/video.mp4?v=5600620863c8 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-15-figma-multiplayer--last-writer-per-property Three people edit one Figma button at once. Who wins? https://media.himanshukukreja.in/lectures/shorts--bonus-15-figma-multiplayer--last-writer-per-property/poster.jpg?v=8f9a1b6af0de Side quest 15 · Figma: Three people edit one Figma button at once. Who wins? https://media.himanshukukreja.in/lectures/shorts--bonus-15-figma-multiplayer--last-writer-per-property/video.mp4?v=8f9a1b6af0de 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-15-figma-multiplayer--no-flicker-rule Why your Figma layer never jumps under your cursor https://media.himanshukukreja.in/lectures/shorts--bonus-15-figma-multiplayer--no-flicker-rule/poster.jpg?v=4300694736eb Side quest 15 · Figma: Why your Figma layer never jumps under your cursor https://media.himanshukukreja.in/lectures/shorts--bonus-15-figma-multiplayer--no-flicker-rule/video.mp4?v=4300694736eb 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-16-bookmyshow-seat-booking--all-or-nothing Two families, the same two seats, the same second https://media.himanshukukreja.in/lectures/shorts--bonus-16-bookmyshow-seat-booking--all-or-nothing/poster.jpg?v=06d0666570b7 Side quest 16 · BookMyShow: Two families, the same two seats, the same second https://media.himanshukukreja.in/lectures/shorts--bonus-16-bookmyshow-seat-booking--all-or-nothing/video.mp4?v=06d0666570b7 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-16-bookmyshow-seat-booking--paid-too-late Paid after the seat hold expired: who gets the seat? https://media.himanshukukreja.in/lectures/shorts--bonus-16-bookmyshow-seat-booking--paid-too-late/poster.jpg?v=bb10445ce2b8 Side quest 16 · BookMyShow: Paid after the seat hold expired: who gets the seat? https://media.himanshukukreja.in/lectures/shorts--bonus-16-bookmyshow-seat-booking--paid-too-late/video.mp4?v=bb10445ce2b8 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-16-bookmyshow-seat-booking--waiting-is-the-cost 13 million people, 1.5 lakh tickets: the waiting is the cost https://media.himanshukukreja.in/lectures/shorts--bonus-16-bookmyshow-seat-booking--waiting-is-the-cost/poster.jpg?v=dfbe99f2cd68 Side quest 16 · BookMyShow: 13 million people, 1.5 lakh tickets: the waiting is the cost https://media.himanshukukreja.in/lectures/shorts--bonus-16-bookmyshow-seat-booking--waiting-is-the-cost/video.mp4?v=dfbe99f2cd68 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-17-swiggy-food-delivery--just-in-time-dispatch Don't send the nearest rider. Not yet. https://media.himanshukukreja.in/lectures/shorts--bonus-17-swiggy-food-delivery--just-in-time-dispatch/poster.jpg?v=3ae5bd471b81 Side quest 17 · Swiggy: Don't send the nearest rider. Not yet. https://media.himanshukukreja.in/lectures/shorts--bonus-17-swiggy-food-delivery--just-in-time-dispatch/video.mp4?v=3ae5bd471b81 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-17-swiggy-food-delivery--promise-a-quantile Why your delivery app never shows the average https://media.himanshukukreja.in/lectures/shorts--bonus-17-swiggy-food-delivery--promise-a-quantile/poster.jpg?v=1cca971dfe96 Side quest 17 · Swiggy: Why your delivery app never shows the average https://media.himanshukukreja.in/lectures/shorts--bonus-17-swiggy-food-delivery--promise-a-quantile/video.mp4?v=1cca971dfe96 93 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-17-swiggy-food-delivery--twenty-second-rounds Nearest rider for every order? Everyone loses. https://media.himanshukukreja.in/lectures/shorts--bonus-17-swiggy-food-delivery--twenty-second-rounds/poster.jpg?v=0619af012f02 Side quest 17 · Swiggy: Nearest rider for every order? Everyone loses. https://media.himanshukukreja.in/lectures/shorts--bonus-17-swiggy-food-delivery--twenty-second-rounds/video.mp4?v=0619af012f02 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-18-razorpay-payment-gateway--exactly-once-lives Tap Pay twice. Get charged once. https://media.himanshukukreja.in/lectures/shorts--bonus-18-razorpay-payment-gateway--exactly-once-lives/poster.jpg?v=1f004ff067f1 Side quest 18 · Razorpay: Tap Pay twice. Get charged once. https://media.himanshukukreja.in/lectures/shorts--bonus-18-razorpay-payment-gateway--exactly-once-lives/video.mp4?v=1f004ff067f1 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-18-razorpay-payment-gateway--route-per-slice One bank route is failing. The average says it's fine. https://media.himanshukukreja.in/lectures/shorts--bonus-18-razorpay-payment-gateway--route-per-slice/poster.jpg?v=26fb9db96e24 Side quest 18 · Razorpay: One bank route is failing. The average says it's fine. https://media.himanshukukreja.in/lectures/shorts--bonus-18-razorpay-payment-gateway--route-per-slice/video.mp4?v=26fb9db96e24 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-18-razorpay-payment-gateway--silence-is-unknown The bank never answered. Did the money move? https://media.himanshukukreja.in/lectures/shorts--bonus-18-razorpay-payment-gateway--silence-is-unknown/poster.jpg?v=b9cc1c01de1c Side quest 18 · Razorpay: The bank never answered. Did the money move? https://media.himanshukukreja.in/lectures/shorts--bonus-18-razorpay-payment-gateway--silence-is-unknown/video.mp4?v=b9cc1c01de1c 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-19-youtube-video-platform--chunk-the-video A two-hour film would hold one worker for hours. So cut it up. https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--chunk-the-video/poster.jpg?v=bab550d2f619 Side quest 19 · YouTube: A two-hour film would hold one worker for hours. So cut it up. https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--chunk-the-video/video.mp4?v=bab550d2f619 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-19-youtube-video-platform--counting-views Why YouTube can't just do views + 1 https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--counting-views/poster.jpg?v=38ba809e116d Side quest 19 · YouTube: Why YouTube can't just do views + 1 https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--counting-views/video.mp4?v=38ba809e116d 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-19-youtube-video-platform--resume-the-upload Your upload dies at 1.1 GB. Where does it resume? https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--resume-the-upload/poster.jpg?v=e44b988da5ea Side quest 19 · YouTube: Your upload dies at 1.1 GB. Where does it resume? https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--resume-the-upload/video.mp4?v=e44b988da5ea 96 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-19-youtube-video-platform--twenty-of-twenty-billion Scoring every video for you would take 46 days https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--twenty-of-twenty-billion/poster.jpg?v=d4faf8e92ff4 Side quest 19 · YouTube: Scoring every video for you would take 46 days https://media.himanshukukreja.in/lectures/shorts--bonus-19-youtube-video-platform--twenty-of-twenty-billion/video.mp4?v=d4faf8e92ff4 96 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-20-google-docs-collaboration--easy-as-123 Two correct edits. One garbled sentence. https://media.himanshukukreja.in/lectures/shorts--bonus-20-google-docs-collaboration--easy-as-123/poster.jpg?v=f744733ac885 Side quest 20 · Google Docs: Two correct edits. One garbled sentence. https://media.himanshukukreja.in/lectures/shorts--bonus-20-google-docs-collaboration--easy-as-123/video.mp4?v=f744733ac885 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-20-google-docs-collaboration--restore-forward Put the doc back to 11:45. Forty people are still typing. https://media.himanshukukreja.in/lectures/shorts--bonus-20-google-docs-collaboration--restore-forward/poster.jpg?v=36b12c871fd1 Side quest 20 · Google Docs: Put the doc back to 11:45. Forty people are still typing. https://media.himanshukukreja.in/lectures/shorts--bonus-20-google-docs-collaboration--restore-forward/video.mp4?v=36b12c871fd1 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-20-google-docs-collaboration--three-days-offline Three days offline: 144 million transforms, or one? https://media.himanshukukreja.in/lectures/shorts--bonus-20-google-docs-collaboration--three-days-offline/poster.jpg?v=6ff3e093c2f4 Side quest 20 · Google Docs: Three days offline: 144 million transforms, or one? https://media.himanshukukreja.in/lectures/shorts--bonus-20-google-docs-collaboration--three-days-offline/video.mp4?v=6ff3e093c2f4 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-21-instagram-feed--celebrity-fanout One post, 400 million followers: push or pull? https://media.himanshukukreja.in/lectures/shorts--bonus-21-instagram-feed--celebrity-fanout/poster.jpg?v=cf1ab30c0db5 Side quest 21 · Instagram: One post, 400 million followers: push or pull? https://media.himanshukukreja.in/lectures/shorts--bonus-21-instagram-feed--celebrity-fanout/video.mp4?v=cf1ab30c0db5 98 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-21-instagram-feed--repackage-dont-encode 86 seconds of CPU, or 0.36? Instagram's video trick https://media.himanshukukreja.in/lectures/shorts--bonus-21-instagram-feed--repackage-dont-encode/poster.jpg?v=95b18915b9dc Side quest 21 · Instagram: 86 seconds of CPU, or 0.36? Instagram's video trick https://media.himanshukukreja.in/lectures/shorts--bonus-21-instagram-feed--repackage-dont-encode/video.mp4?v=95b18915b9dc 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-21-instagram-feed--stories-expire At hour 24, nothing deletes your story https://media.himanshukukreja.in/lectures/shorts--bonus-21-instagram-feed--stories-expire/poster.jpg?v=69b16598ce5f Side quest 21 · Instagram: At hour 24, nothing deletes your story https://media.himanshukukreja.in/lectures/shorts--bonus-21-instagram-feed--stories-expire/video.mp4?v=69b16598ce5f 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-22-google-maps--beyond-dijkstra Dijkstra would need 134,000 cores https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--beyond-dijkstra/poster.jpg?v=61b4fa1d239e Side quest 22 · Google Maps: Dijkstra would need 134,000 cores https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--beyond-dijkstra/video.mp4?v=61b4fa1d239e 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-22-google-maps--one-flyover-seventeen-tiles A new flyover opens. Which map tiles change? https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--one-flyover-seventeen-tiles/poster.jpg?v=167e33585ab4 Side quest 22 · Google Maps: A new flyover opens. Which map tiles change? https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--one-flyover-seventeen-tiles/video.mp4?v=167e33585ab4 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-22-google-maps--phones-to-speeds A bus waits at a stop. Why doesn't the road turn red? https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--phones-to-speeds/poster.jpg?v=8c7cd68d2eff Side quest 22 · Google Maps: A bus waits at a stop. Why doesn't the road turn red? https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--phones-to-speeds/video.mp4?v=8c7cd68d2eff 102 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-22-google-maps--time-for-arrival Your map timed a jam that hasn't formed yet https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--time-for-arrival/poster.jpg?v=8c0793572541 Side quest 22 · Google Maps: Your map timed a jam that hasn't formed yet https://media.himanshukukreja.in/lectures/shorts--bonus-22-google-maps--time-for-arrival/video.mp4?v=8c0793572541 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-23-zoom-video-meetings--a-layer-per-receiver Your 4G dies in a cab. Nobody else's video gets worse. https://media.himanshukukreja.in/lectures/shorts--bonus-23-zoom-video-meetings--a-layer-per-receiver/poster.jpg?v=d3beb43887c9 Side quest 23 · Zoom: Your 4G dies in a cab. Nobody else's video gets worse. https://media.himanshukukreja.in/lectures/shorts--bonus-23-zoom-video-meetings--a-layer-per-receiver/video.mp4?v=d3beb43887c9 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-23-zoom-video-meetings--late-is-lost Why video calls don't trust TCP https://media.himanshukukreja.in/lectures/shorts--bonus-23-zoom-video-meetings--late-is-lost/poster.jpg?v=b84cf3020c3a Side quest 23 · Zoom: Why video calls don't trust TCP https://media.himanshukukreja.in/lectures/shorts--bonus-23-zoom-video-meetings--late-is-lost/video.mp4?v=b84cf3020c3a 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-23-zoom-video-meetings--route-dont-mix 360,000 servers or 4,500? Route, don't mix https://media.himanshukukreja.in/lectures/shorts--bonus-23-zoom-video-meetings--route-dont-mix/poster.jpg?v=164289993661 Side quest 23 · Zoom: 360,000 servers or 4,500? Route, don't mix https://media.himanshukukreja.in/lectures/shorts--bonus-23-zoom-video-meetings--route-dont-mix/video.mp4?v=164289993661 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-24-airbnb-stays-marketplace--365-bits Nine million homes, a whole year, under half a gigabyte https://media.himanshukukreja.in/lectures/shorts--bonus-24-airbnb-stays-marketplace--365-bits/poster.jpg?v=9cead59c1452 Side quest 24 · Airbnb: Nine million homes, a whole year, under half a gigabyte https://media.himanshukukreja.in/lectures/shorts--bonus-24-airbnb-stays-marketplace--365-bits/video.mp4?v=9cead59c1452 99 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-24-airbnb-stays-marketplace--maps-arent-lists Fewer homes on the map, more bookings https://media.himanshukukreja.in/lectures/shorts--bonus-24-airbnb-stays-marketplace--maps-arent-lists/poster.jpg?v=2a5073560832 Side quest 24 · Airbnb: Fewer homes on the map, more bookings https://media.himanshukukreja.in/lectures/shorts--bonus-24-airbnb-stays-marketplace--maps-arent-lists/video.mp4?v=2a5073560832 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-24-airbnb-stays-marketplace--the-blind-window One homestay, three sites, and a file read every 3 hours https://media.himanshukukreja.in/lectures/shorts--bonus-24-airbnb-stays-marketplace--the-blind-window/poster.jpg?v=5f862b7abe9d Side quest 24 · Airbnb: One homestay, three sites, and a file read every 3 hours https://media.himanshukukreja.in/lectures/shorts--bonus-24-airbnb-stays-marketplace--the-blind-window/video.mp4?v=5f862b7abe9d 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-25-dream11-fantasy-sports--deadline-is-a-state Fifteen million teams, one deadline, and no clock gets a say https://media.himanshukukreja.in/lectures/shorts--bonus-25-dream11-fantasy-sports--deadline-is-a-state/poster.jpg?v=b4618f47d56a Side quest 25 · Dream11: Fifteen million teams, one deadline, and no clock gets a say https://media.himanshukukreja.in/lectures/shorts--bonus-25-dream11-fantasy-sports--deadline-is-a-state/video.mp4?v=b4618f47d56a 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-25-dream11-fantasy-sports--rank-by-counting 7.9 million ranks after every ball, without sorting https://media.himanshukukreja.in/lectures/shorts--bonus-25-dream11-fantasy-sports--rank-by-counting/poster.jpg?v=64cb1f71366b Side quest 25 · Dream11: 7.9 million ranks after every ball, without sorting https://media.himanshukukreja.in/lectures/shorts--bonus-25-dream11-fantasy-sports--rank-by-counting/video.mp4?v=64cb1f71366b 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-25-dream11-fantasy-sports--sharded-spots Ten million spots, 15,000 joins a second, never oversold https://media.himanshukukreja.in/lectures/shorts--bonus-25-dream11-fantasy-sports--sharded-spots/poster.jpg?v=73d391e1646f Side quest 25 · Dream11: Ten million spots, 15,000 joins a second, never oversold https://media.himanshukukreja.in/lectures/shorts--bonus-25-dream11-fantasy-sports--sharded-spots/video.mp4?v=73d391e1646f 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-26-truecaller-caller-id--forty-reports-zero-calls 40 spam reports. Not one real call. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--forty-reports-zero-calls/poster.jpg?v=4f3e46b380ee Side quest 26 · Truecaller: 40 spam reports. Not one real call. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--forty-reports-zero-calls/video.mp4?v=4f3e46b380ee 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-26-truecaller-caller-id--never-learns-the-question It names the caller. It never learns who asked. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--never-learns-the-question/poster.jpg?v=08fe21d82bd9 Side quest 26 · Truecaller: It names the caller. It never learns who asked. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--never-learns-the-question/video.mp4?v=08fe21d82bd9 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-26-truecaller-caller-id--overwrite-never-delete One verdict change. Fifty cache misses a second. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--overwrite-never-delete/poster.jpg?v=c22c7ef1bf25 Side quest 26 · Truecaller: One verdict change. Fifty cache misses a second. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--overwrite-never-delete/video.mp4?v=c22c7ef1bf25 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-26-truecaller-caller-id--the-cache-in-your-pocket The most important cache is on your phone. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--the-cache-in-your-pocket/poster.jpg?v=61af4da330ef Side quest 26 · Truecaller: The most important cache is on your phone. https://media.himanshukukreja.in/lectures/shorts--bonus-26-truecaller-caller-id--the-cache-in-your-pocket/video.mp4?v=61af4da330ef 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-27-flipkart-big-billion-days--a-line-per-deal 5,000 phones, 300,000 taps, ten seconds https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--a-line-per-deal/poster.jpg?v=89a61641fe57 Side quest 27 · Flipkart: 5,000 phones, 300,000 taps, ten seconds https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--a-line-per-deal/video.mp4?v=89a61641fe57 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-27-flipkart-big-billion-days--midnight-is-one-switch Millions of prices change at midnight. Nothing expires. https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--midnight-is-one-switch/poster.jpg?v=79d92c8ba9d4 Side quest 27 · Flipkart: Millions of prices change at midnight. Nothing expires. https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--midnight-is-one-switch/video.mp4?v=79d92c8ba9d4 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-27-flipkart-big-billion-days--the-date-is-a-promise Delivery by Tuesday is a promise about a truck https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--the-date-is-a-promise/poster.jpg?v=12661c012c08 Side quest 27 · Flipkart: Delivery by Tuesday is a promise about a truck https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--the-date-is-a-promise/video.mp4?v=12661c012c08 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-27-flipkart-big-billion-days--unknown-is-not-failed The bank didn't answer. Did Rohan pay? https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--unknown-is-not-failed/poster.jpg?v=ff3a1337719a Side quest 27 · Flipkart: The bank didn't answer. Did Rohan pay? https://media.himanshukukreja.in/lectures/shorts--bonus-27-flipkart-big-billion-days--unknown-is-not-failed/video.mp4?v=ff3a1337719a 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-28-gmail-email-at-scale--250-is-a-promise Two words that decide who owns your email: 250 OK https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--250-is-a-promise/poster.jpg?v=24fb5ec09edb Side quest 28 · Gmail: Two words that decide who owns your email: 250 OK https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--250-is-a-promise/video.mp4?v=24fb5ec09edb 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-28-gmail-email-at-scale--a-billion-small-indexes 100 petabytes of index, every search under a second https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--a-billion-small-indexes/poster.jpg?v=7ba28a4dfd09 Side quest 28 · Gmail: 100 petabytes of index, every search under a second https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--a-billion-small-indexes/video.mp4?v=7ba28a4dfd09 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-28-gmail-email-at-scale--saved-by-tape Multiple copies, one bug: the night tape saved Gmail https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--saved-by-tape/poster.jpg?v=a5a1486893ee Side quest 28 · Gmail: Multiple copies, one bug: the night tape saved Gmail https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--saved-by-tape/video.mp4?v=a5a1486893ee 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-28-gmail-email-at-scale--the-refund-that-isnt It passed SPF and DKIM. It was still phishing. https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--the-refund-that-isnt/poster.jpg?v=35c5dd67a205 Side quest 28 · Gmail: It passed SPF and DKIM. It was still phishing. https://media.himanshukukreja.in/lectures/shorts--bonus-28-gmail-email-at-scale--the-refund-that-isnt/video.mp4?v=35c5dd67a205 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-29-github-code-hosting--grep-would-take-96-seconds Search all of GitHub with grep? 96 seconds a search https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--grep-would-take-96-seconds/poster.jpg?v=983f7fbda5ab Side quest 29 · GitHub: Search all of GitHub with grep? 96 seconds a search https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--grep-would-take-96-seconds/video.mp4?v=983f7fbda5ab 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-29-github-code-hosting--one-branch-at-a-time Five copies, one lock: why GitHub now votes one branch at a time https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--one-branch-at-a-time/poster.jpg?v=78189fa8998f Side quest 29 · GitHub: Five copies, one lock: why GitHub now votes one branch at a time https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--one-branch-at-a-time/video.mp4?v=78189fa8998f 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-29-github-code-hosting--ten-seconds-or-failed GitHub gives your webhook 10 seconds. Then it's a failure https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--ten-seconds-or-failed/poster.jpg?v=2037fd827176 Side quest 29 · GitHub: GitHub gives your webhook 10 seconds. Then it's a failure https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--ten-seconds-or-failed/video.mp4?v=2037fd827176 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-29-github-code-hosting--the-backlog-that-fed-itself GitHub's runners got stuck retrying revoked jobs: the backlog that fed itself https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--the-backlog-that-fed-itself/poster.jpg?v=245488597e0d Side quest 29 · GitHub: GitHub's runners got stuck retrying revoked jobs: the backlog that fed itself https://media.himanshukukreja.in/lectures/shorts--bonus-29-github-code-hosting--the-backlog-that-fed-itself/video.mp4?v=245488597e0d 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-30-tiktok-for-you-feed--a-skip-is-a-label 0.8 seconds, no tap: the swipe that teaches the feed https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--a-skip-is-a-label/poster.jpg?v=80ed458938b0 Side quest 30 · TikTok: 0.8 seconds, no tap: the swipe that teaches the feed https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--a-skip-is-a-label/video.mp4?v=80ed458938b0 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-30-tiktok-for-you-feed--never-share-a-row Your video shares a vector with spam https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--never-share-a-row/poster.jpg?v=3e9747119954 Side quest 30 · TikTok: Your video shares a vector with spam https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--never-share-a-row/video.mp4?v=3e9747119954 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-30-tiktok-for-you-feed--terabytes-every-minute A model of several terabytes, updated every minute https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--terabytes-every-minute/poster.jpg?v=511759128e2a Side quest 30 · TikTok: A model of several terabytes, updated every minute https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--terabytes-every-minute/video.mp4?v=511759128e2a 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--bonus-30-tiktok-for-you-feed--the-song-at-9pm A new song at 9 pm, and a partition on fire https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--the-song-at-9pm/poster.jpg?v=1894e5614721 Side quest 30 · TikTok: A new song at 9 pm, and a partition on fire https://media.himanshukukreja.in/lectures/shorts--bonus-30-tiktok-for-you-feed--the-song-at-9pm/video.mp4?v=1894e5614721 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--bridgelink-remote-android-testing--hung-is-unhealthy The tunnel was up. The phone behind it was dead. https://media.himanshukukreja.in/lectures/shorts--case-files--bridgelink-remote-android-testing--hung-is-unhealthy/poster.jpg?v=f0bc86c1ad1f Case file · BridgeLink: The tunnel was up. The phone behind it was dead. https://media.himanshukukreja.in/lectures/shorts--case-files--bridgelink-remote-android-testing--hung-is-unhealthy/video.mp4?v=f0bc86c1ad1f 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--bridgelink-remote-android-testing--secret-isnt-encryption Your tunnel has a secret. Your traffic is still plaintext. https://media.himanshukukreja.in/lectures/shorts--case-files--bridgelink-remote-android-testing--secret-isnt-encryption/poster.jpg?v=dd660bc33b5f Case file · BridgeLink: Your tunnel has a secret. Your traffic is still plaintext. https://media.himanshukukreja.in/lectures/shorts--case-files--bridgelink-remote-android-testing--secret-isnt-encryption/video.mp4?v=dd660bc33b5f 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--cdn-cache-poisoning-disaster--probe-as-three-users To catch a leaking cache, pretend to be three people https://media.himanshukukreja.in/lectures/shorts--case-files--cdn-cache-poisoning-disaster--probe-as-three-users/poster.jpg?v=6bbfcd24a90d Case file · ShopFast: To catch a leaking cache, pretend to be three people https://media.himanshukukreja.in/lectures/shorts--case-files--cdn-cache-poisoning-disaster--probe-as-three-users/video.mp4?v=6bbfcd24a90d 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--cdn-cache-poisoning-disaster--someone-elses-cart 47 shoppers got the same cart. Every dashboard stayed green. https://media.himanshukukreja.in/lectures/shorts--case-files--cdn-cache-poisoning-disaster--someone-elses-cart/poster.jpg?v=22418b13d8c2 Case file · ShopFast: 47 shoppers got the same cart. Every dashboard stayed green. https://media.himanshukukreja.in/lectures/shorts--case-files--cdn-cache-poisoning-disaster--someone-elses-cart/video.mp4?v=22418b13d8c2 94 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--box-twenty-one A list had 20 items. A rule asked for the 21st. https://media.himanshukukreja.in/lectures/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--box-twenty-one/poster.jpg?v=fae77bc4983a Case file · CrowdStrike: A list had 20 items. A rule asked for the 21st. https://media.himanshukukreja.in/lectures/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--box-twenty-one/video.mp4?v=fae77bc4983a 96 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--canary-that-wasnt One update, every machine at once: the canary CrowdStrike didn't have https://media.himanshukukreja.in/lectures/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--canary-that-wasnt/poster.jpg?v=d0d35ba3211e Case file · CrowdStrike: One update, every machine at once: the canary CrowdStrike didn't have https://media.himanshukukreja.in/lectures/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--canary-that-wasnt/video.mp4?v=d0d35ba3211e 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--cant-phone-home CrowdStrike fixed the file in 78 minutes. The machines took days. https://media.himanshukukreja.in/lectures/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--cant-phone-home/poster.jpg?v=66d63df64d94 Case file · CrowdStrike: CrowdStrike fixed the file in 78 minutes. The machines took days. https://media.himanshukukreja.in/lectures/shorts--case-files--crowdstrike-one-file-8-million-blue-screens--cant-phone-home/video.mp4?v=66d63df64d94 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--digipin-scalable-location-service--computed-not-assigned 205 billion squares of India, and no list of names https://media.himanshukukreja.in/lectures/shorts--case-files--digipin-scalable-location-service--computed-not-assigned/poster.jpg?v=0541cfb44890 Case file · DIGIPIN: 205 billion squares of India, and no list of names https://media.himanshukukreja.in/lectures/shorts--case-files--digipin-scalable-location-service--computed-not-assigned/video.mp4?v=0541cfb44890 103 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--distributed-transactions-2pc-saga-pattern--flight-car-no-hotel All or nothing: a flight, a car, and no hotel https://media.himanshukukreja.in/lectures/shorts--case-files--distributed-transactions-2pc-saga-pattern--flight-car-no-hotel/poster.jpg?v=d7724c1a0274 Case file · WonderTravel: All or nothing: a flight, a car, and no hotel https://media.himanshukukreja.in/lectures/shorts--case-files--distributed-transactions-2pc-saga-pattern--flight-car-no-hotel/video.mp4?v=d7724c1a0274 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--hotstar-25-million-viewers-one-match--fake-crowd Before match night, Hotstar attacked itself with a fake crowd https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--fake-crowd/poster.jpg?v=ed9a4af826f8 Case file · Hotstar: Before match night, Hotstar attacked itself with a fake crowd https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--fake-crowd/video.mp4?v=ed9a4af826f8 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--hotstar-25-million-viewers-one-match--order-food-first A million new viewers a minute. Servers took six to start. https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--order-food-first/poster.jpg?v=e68e823ed93b Case file · Hotstar: A million new viewers a minute. Servers took six to start. https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--order-food-first/video.mp4?v=e68e823ed93b 102 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--hotstar-25-million-viewers-one-match--the-drop-not-the-peak The peak didn't hurt Hotstar. The run out did. https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--the-drop-not-the-peak/poster.jpg?v=04ba04c5ae64 Case file · Hotstar: The peak didn't hurt Hotstar. The run out did. https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--the-drop-not-the-peak/video.mp4?v=04ba04c5ae64 94 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--hotstar-25-million-viewers-one-match--video-plays-on Login failing? Hotstar let you watch anyway. https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--video-plays-on/poster.jpg?v=43138eb2cd18 Case file · Hotstar: Login failing? Hotstar let you watch anyway. https://media.himanshukukreja.in/lectures/shorts--case-files--hotstar-25-million-viewers-one-match--video-plays-on/video.mp4?v=43138eb2cd18 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--integer-overflow-auto-increment-crisis--four-bytes-saved You saved 4 bytes a row. Now the fix takes up to 11 hours. https://media.himanshukukreja.in/lectures/shorts--case-files--integer-overflow-auto-increment-crisis--four-bytes-saved/poster.jpg?v=779b6b1b2b17 Case file · Integer overflow: You saved 4 bytes a row. Now the fix takes up to 11 hours. https://media.himanshukukreja.in/lectures/shorts--case-files--integer-overflow-auto-increment-crisis--four-bytes-saved/video.mp4?v=779b6b1b2b17 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--integer-overflow-auto-increment-crisis--silent-ceiling 2,147,483,647: the number that silently stopped every insert https://media.himanshukukreja.in/lectures/shorts--case-files--integer-overflow-auto-increment-crisis--silent-ceiling/poster.jpg?v=63d069a258cf Case file · Integer overflow: 2,147,483,647: the number that silently stopped every insert https://media.himanshukukreja.in/lectures/shorts--case-files--integer-overflow-auto-increment-crisis--silent-ceiling/video.mp4?v=63d069a258cf 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--ios-bridge-cross-platform-streaming--newest-frame-wins To make an iPhone stream feel live, throw frames away https://media.himanshukukreja.in/lectures/shorts--case-files--ios-bridge-cross-platform-streaming--newest-frame-wins/poster.jpg?v=5ac9d2e778c3 Case file · iOS Bridge: To make an iPhone stream feel live, throw frames away https://media.himanshukukreja.in/lectures/shorts--case-files--ios-bridge-cross-platform-streaming--newest-frame-wins/video.mp4?v=5ac9d2e778c3 96 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--irctc-tatkal-500-seats-2-million-users--looking-vs-buying Your refresh can cost a stranger their Tatkal seat https://media.himanshukukreja.in/lectures/shorts--case-files--irctc-tatkal-500-seats-2-million-users--looking-vs-buying/poster.jpg?v=ab0e44fe2792 Case file · IRCTC Tatkal: Your refresh can cost a stranger their Tatkal seat https://media.himanshukukreja.in/lectures/shorts--case-files--irctc-tatkal-500-seats-2-million-users--looking-vs-buying/video.mp4?v=ab0e44fe2792 93 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--leader-follower-replication-node-outages--replicate-by-value The leader died right after confirming your payment. Is it gone? https://media.himanshukukreja.in/lectures/shorts--case-files--leader-follower-replication-node-outages--replicate-by-value/poster.jpg?v=1c029c02e5a6 Case file · StreamFlix: The leader died right after confirming your payment. Is it gone? https://media.himanshukukreja.in/lectures/shorts--case-files--leader-follower-replication-node-outages--replicate-by-value/video.mp4?v=1c029c02e5a6 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--scalable-spam-detection-bloom-filter--the-rebuild-gap The nightly rebuild that could let a phishing link through https://media.himanshukukreja.in/lectures/shorts--case-files--scalable-spam-detection-bloom-filter--the-rebuild-gap/poster.jpg?v=3bb2746f9b6c Case file · GlobalForum: The nightly rebuild that could let a phishing link through https://media.himanshukukreja.in/lectures/shorts--case-files--scalable-spam-detection-bloom-filter--the-rebuild-gap/video.mp4?v=3bb2746f9b6c 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--scalable-spam-detection-bloom-filter--trust-the-hits Under attack, this spam filter blocks clean links on purpose https://media.himanshukukreja.in/lectures/shorts--case-files--scalable-spam-detection-bloom-filter--trust-the-hits/poster.jpg?v=bb8c05c6f7fc Case file · GlobalForum: Under attack, this spam filter blocks clean links on purpose https://media.himanshukukreja.in/lectures/shorts--case-files--scalable-spam-detection-bloom-filter--trust-the-hits/video.mp4?v=bb8c05c6f7fc 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--websockets-vs-webrtc-video-communication--chat-fine-video-dies Same WebSocket: chat was instant, video was seconds behind https://media.himanshukukreja.in/lectures/shorts--case-files--websockets-vs-webrtc-video-communication--chat-fine-video-dies/poster.jpg?v=b315bc1c9d93 Case file · ConnectNow: Same WebSocket: chat was instant, video was seconds behind https://media.himanshukukreja.in/lectures/shorts--case-files--websockets-vs-webrtc-video-communication--chat-fine-video-dies/video.mp4?v=b315bc1c9d93 108 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--case-files--websockets-vs-webrtc-video-communication--mesh-breaks-at-ten Peer-to-peer video works for two. At ten, it needs 54 Mbps each. https://media.himanshukukreja.in/lectures/shorts--case-files--websockets-vs-webrtc-video-communication--mesh-breaks-at-ten/poster.jpg?v=b2bfd62a7b1f Case file · ConnectNow: Peer-to-peer video works for two. At ten, it needs 54 Mbps each. https://media.himanshukukreja.in/lectures/shorts--case-files--websockets-vs-webrtc-video-communication--mesh-breaks-at-ten/video.mp4?v=b2bfd62a7b1f 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-01-parking-lot--new-tariff-new-class Minute 75: a new parking rule. How many lines do you edit? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-01-parking-lot--new-tariff-new-class/poster.jpg?v=184100a51741 LLD · Parking lot: Minute 75: a new parking rule. How many lines do you edit? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-01-parking-lot--new-tariff-new-class/video.mp4?v=184100a51741 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-01-parking-lot--two-gates-one-spot Two gates, one free spot, two tickets https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-01-parking-lot--two-gates-one-spot/poster.jpg?v=09b8ac602da2 LLD · Parking lot: Two gates, one free spot, two tickets https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-01-parking-lot--two-gates-one-spot/video.mp4?v=09b8ac602da2 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-02-lru-cache--get-is-a-write It's only a read, so it doesn't need a lock. Wrong. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-02-lru-cache--get-is-a-write/poster.jpg?v=7c29fc26f4f2 LLD · LRU cache: It's only a read, so it doesn't need a lock. Wrong. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-02-lru-cache--get-is-a-write/video.mp4?v=7c29fc26f4f2 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-02-lru-cache--map-plus-list Why an LRU cache needs a hash map and a linked list https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-02-lru-cache--map-plus-list/poster.jpg?v=0ad32f7db51a LLD · LRU cache: Why an LRU cache needs a hash map and a linked list https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-02-lru-cache--map-plus-list/video.mp4?v=0ad32f7db51a 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-03-rate-limiter--inject-the-clock Your rate limiter test waits a whole minute. It shouldn't. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-03-rate-limiter--inject-the-clock/poster.jpg?v=468d406264c0 LLD · Rate limiter: Your rate limiter test waits a whole minute. It shouldn't. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-03-rate-limiter--inject-the-clock/video.mp4?v=468d406264c0 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-03-rate-limiter--two-buckets-one-client A new client's first two requests got two rate-limit buckets https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-03-rate-limiter--two-buckets-one-client/poster.jpg?v=c533ee17caed LLD · Rate limiter: A new client's first two requests got two rate-limit buckets https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-03-rate-limiter--two-buckets-one-client/video.mp4?v=c533ee17caed 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-04-elevator-system--nine-one-eight Buttons 9, 1, 8: why your elevator shouldn't obey the order https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-04-elevator-system--nine-one-eight/poster.jpg?v=bf836b3b47eb LLD · Elevator system: Buttons 9, 1, 8: why your elevator shouldn't obey the order https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-04-elevator-system--nine-one-eight/video.mp4?v=bf836b3b47eb 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-04-elevator-system--which-car The elevator one floor away is the wrong one https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-04-elevator-system--which-car/poster.jpg?v=8d41b7af50c7 LLD · Elevator system: The elevator one floor away is the wrong one https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-04-elevator-system--which-car/video.mp4?v=8d41b7af50c7 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-05-movie-ticket-booking--who-owns-the-hold Two tabs, the same seats: who owns the hold? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-05-movie-ticket-booking--who-owns-the-hold/poster.jpg?v=36aa7482725c LLD · Movie ticket booking: Two tabs, the same seats: who owns the hold? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-05-movie-ticket-booking--who-owns-the-hold/video.mp4?v=36aa7482725c 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-06-splitwise--six-debts-three-payments Four friends, six debts, settled in three payments https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-06-splitwise--six-debts-three-payments/poster.jpg?v=be1d7671d16a LLD · Splitwise: Four friends, six debts, settled in three payments https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-06-splitwise--six-debts-three-payments/video.mp4?v=be1d7671d16a 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-06-splitwise--the-extra-paisa Split ₹100 three ways. Where does the last paisa go? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-06-splitwise--the-extra-paisa/poster.jpg?v=fc9bd51b0657 LLD · Splitwise: Split ₹100 three ways. Where does the last paisa go? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-06-splitwise--the-extra-paisa/video.mp4?v=fc9bd51b0657 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-07-vending-machine--greedy-change-fails The vending machine had the coins. Greedy still got stuck. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-07-vending-machine--greedy-change-fails/poster.jpg?v=e47babeb55e2 LLD · Vending machine: The vending machine had the coins. Greedy still got stuck. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-07-vending-machine--greedy-change-fails/video.mp4?v=e47babeb55e2 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-07-vending-machine--sixteen-answers Four states, four buttons, sixteen answers https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-07-vending-machine--sixteen-answers/poster.jpg?v=016b0269d017 LLD · Vending machine: Four states, four buttons, sixteen answers https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-07-vending-machine--sixteen-answers/video.mp4?v=016b0269d017 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-08-pub-sub-logger--broken-sink-loop The log disk is full. So the logger logs that. To the disk. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-08-pub-sub-logger--broken-sink-loop/poster.jpg?v=04abcc379ae9 LLD · Logging framework: The log disk is full. So the logger logs that. To the disk. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-08-pub-sub-logger--broken-sink-loop/video.mp4?v=04abcc379ae9 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-08-pub-sub-logger--drop-dont-block The disk got slow, and a log line stalled every request https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-08-pub-sub-logger--drop-dont-block/poster.jpg?v=f89dd7258abf LLD · Logging framework: The disk got slow, and a log line stalled every request https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-08-pub-sub-logger--drop-dont-block/video.mp4?v=f89dd7258abf 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-08-pub-sub-logger--redact-before-publish One error log, a full card number inside https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-08-pub-sub-logger--redact-before-publish/poster.jpg?v=bed6576d7b9a LLD · Logging framework: One error log, a full card number inside https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-08-pub-sub-logger--redact-before-publish/video.mp4?v=bed6576d7b9a 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-09-snake-and-ladder--chain-becomes-a-loop A ladder that lands on a snake's head can loop forever https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-09-snake-and-ladder--chain-becomes-a-loop/poster.jpg?v=542decd2c060 LLD · Snake and Ladder: A ladder that lands on a snake's head can loop forever https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-09-snake-and-ladder--chain-becomes-a-loop/video.mp4?v=542decd2c060 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-09-snake-and-ladder--double-tap Her phone lagged, she tapped roll twice. Two turns? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-09-snake-and-ladder--double-tap/poster.jpg?v=3c2b54339a9e LLD · Snake and Ladder: Her phone lagged, she tapped roll twice. Two turns? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-09-snake-and-ladder--double-tap/video.mp4?v=3c2b54339a9e 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-10-chess--en-passant-undo A capture that lands on an empty square. Now undo it. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-10-chess--en-passant-undo/poster.jpg?v=9a2201863976 LLD · Chess: A capture that lands on an empty square. Now undo it. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-10-chess--en-passant-undo/video.mp4?v=9a2201863976 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-10-chess--pinned-bishop The bishop can see d3. It still can't go there. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-10-chess--pinned-bishop/poster.jpg?v=e6e2f78dd3f1 LLD · Chess: The bishop can see d3. It still can't go there. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-10-chess--pinned-bishop/video.mp4?v=e6e2f78dd3f1 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-11-atm--debit-before-dispense The bank said yes. Then the notes jammed. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-11-atm--debit-before-dispense/poster.jpg?v=7ff0cf17f165 LLD · ATM: The bank said yes. Then the notes jammed. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-11-atm--debit-before-dispense/video.mp4?v=7ff0cf17f165 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-11-atm--greedy-fails-at-600 ₹600, plenty of notes, and a greedy ATM gets stuck https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-11-atm--greedy-fails-at-600/poster.jpg?v=ade86bce5110 LLD · ATM: ₹600, plenty of notes, and a greedy ATM gets stuck https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-11-atm--greedy-fails-at-600/video.mp4?v=ade86bce5110 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-12-library-management--hold-shelf Rohan waited in line. A walk-in took his book. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-12-library-management--hold-shelf/poster.jpg?v=5ee393b2d8bc LLD · Library: Rohan waited in line. A walk-in took his book. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-12-library-management--hold-shelf/video.mp4?v=5ee393b2d8bc 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-12-library-management--title-or-copy Two copies of one book: which one do you reserve? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-12-library-management--title-or-copy/poster.jpg?v=29c3d0768b72 LLD · Library: Two copies of one book: which one do you reserve? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-12-library-management--title-or-copy/video.mp4?v=29c3d0768b72 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-13-hotel-reservation--price-per-night Same room, same Monday: why the fourth guest pays ₹750 more https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-13-hotel-reservation--price-per-night/poster.jpg?v=f0f03ff40ca8 LLD · Hotel Reservation: Same room, same Monday: why the fourth guest pays ₹750 more https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-13-hotel-reservation--price-per-night/video.mp4?v=f0f03ff40ca8 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-13-hotel-reservation--sell-types-not-rooms Every night has a free room, and the guest is still turned away https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-13-hotel-reservation--sell-types-not-rooms/poster.jpg?v=d4e4fbf806fd LLD · Hotel Reservation: Every night has a free room, and the guest is still turned away https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-13-hotel-reservation--sell-types-not-rooms/video.mp4?v=d4e4fbf806fd 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-14-ride-sharing--search-is-a-snapshot Two riders, one nearest driver, the same second https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-14-ride-sharing--search-is-a-snapshot/poster.jpg?v=0b4cf4da58e2 LLD · Ride Sharing: Two riders, one nearest driver, the same second https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-14-ride-sharing--search-is-a-snapshot/video.mp4?v=0b4cf4da58e2 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-14-ride-sharing--surge-fixed-at-booking You booked at no surge. Should you pay surge at drop-off? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-14-ride-sharing--surge-fixed-at-booking/poster.jpg?v=5ba204d4983e LLD · Ride Sharing: You booked at no surge. Should you pay surge at drop-off? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-14-ride-sharing--surge-fixed-at-booking/video.mp4?v=5ba204d4983e 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-15-food-delivery--cancel-meets-ready Cancel and Ready tapped at the same moment. Who wins? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-15-food-delivery--cancel-meets-ready/poster.jpg?v=0d44e522745f LLD · Food Delivery: Cancel and Ready tapped at the same moment. Who wins? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-15-food-delivery--cancel-meets-ready/video.mp4?v=0d44e522745f 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-16-meeting-room-scheduler--strictly-less-than One equals sign blocks every back-to-back meeting https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-16-meeting-room-scheduler--strictly-less-than/poster.jpg?v=bce22ab40bbc LLD · Meeting Rooms: One equals sign blocks every back-to-back meeting https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-16-meeting-room-scheduler--strictly-less-than/video.mp4?v=bce22ab40bbc 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-16-meeting-room-scheduler--two-binary-searches Find every clash in a room with two binary searches https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-16-meeting-room-scheduler--two-binary-searches/poster.jpg?v=674a0833f173 LLD · Meeting Rooms: Find every clash in a room with two binary searches https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-16-meeting-room-scheduler--two-binary-searches/video.mp4?v=674a0833f173 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-17-in-memory-file-system--folders-are-nodes du at any depth, with no type checks https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-17-in-memory-file-system--folders-are-nodes/poster.jpg?v=8ea354c4d6db LLD · File System: du at any depth, with no type checks https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-17-in-memory-file-system--folders-are-nodes/video.mp4?v=8ea354c4d6db 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-17-in-memory-file-system--move-into-itself One mv cuts your home folder off the tree https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-17-in-memory-file-system--move-into-itself/poster.jpg?v=5556dad8ecff LLD · File System: One mv cuts your home folder off the tree https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-17-in-memory-file-system--move-into-itself/video.mp4?v=5556dad8ecff 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-18-text-editor-undo-redo--commands-not-snapshots Same undo history: 100 characters, or 5 million? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-18-text-editor-undo-redo--commands-not-snapshots/poster.jpg?v=d91cb0399f6f LLD · Text Editor: Same undo history: 100 characters, or 5 million? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-18-text-editor-undo-redo--commands-not-snapshots/video.mp4?v=d91cb0399f6f 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-18-text-editor-undo-redo--undo-a-word Ctrl+Z took the word, not the letter. Here's the rule. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-18-text-editor-undo-redo--undo-a-word/poster.jpg?v=cbee689369d4 LLD · Text Editor: Ctrl+Z took the word, not the letter. Here's the rule. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-18-text-editor-undo-redo--undo-a-word/video.mp4?v=cbee689369d4 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-19-online-auction--clock-not-timer The auction ended. A bid a second later still got in. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-19-online-auction--clock-not-timer/poster.jpg?v=a89d3d5d033d LLD · Online Auction: The auction ended. A bid a second later still got in. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-19-online-auction--clock-not-timer/video.mp4?v=a89d3d5d033d 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-19-online-auction--soft-close A bid with 10 seconds left makes the auction longer https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-19-online-auction--soft-close/poster.jpg?v=fba356ff5829 LLD · Online Auction: A bid with 10 seconds left makes the auction longer https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-19-online-auction--soft-close/video.mp4?v=fba356ff5829 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-20-stock-exchange-order-book--one-thread-no-locks A matching engine with zero locks, on purpose https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-20-stock-exchange-order-book--one-thread-no-locks/poster.jpg?v=16de1cd39dc4 LLD · Order Book: A matching engine with zero locks, on purpose https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-20-stock-exchange-order-book--one-thread-no-locks/video.mp4?v=16de1cd39dc4 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-20-stock-exchange-order-book--resting-price You bid ₹102 a share. You paid ₹101 for eight of them. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-20-stock-exchange-order-book--resting-price/poster.jpg?v=b340dbca91ed LLD · Order Book: You bid ₹102 a share. You paid ₹101 for eight of them. https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-20-stock-exchange-order-book--resting-price/video.mp4?v=b340dbca91ed 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-21-task-scheduler-dependencies--count-unmet Build just finished. Which tasks can start now? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-21-task-scheduler-dependencies--count-unmet/poster.jpg?v=5bcbaf5a885b LLD · Task Scheduler: Build just finished. Which tasks can start now? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-21-task-scheduler-dependencies--count-unmet/video.mp4?v=5bcbaf5a885b 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-21-task-scheduler-dependencies--never-finishes Two ways a task scheduler waits forever https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-21-task-scheduler-dependencies--never-finishes/poster.jpg?v=bddc36369b0c LLD · Task Scheduler: Two ways a task scheduler waits forever https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-21-task-scheduler-dependencies--never-finishes/video.mp4?v=bddc36369b0c 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--keys-nobody-reads An expired key nobody reads never leaves memory https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--keys-nobody-reads/poster.jpg?v=8553a21fba59 LLD · Key-Value Store: An expired key nobody reads never leaves memory https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--keys-nobody-reads/video.mp4?v=8553a21fba59 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--lost-update Two deposits, one balance, and one silently vanishes https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--lost-update/poster.jpg?v=4cc3398b47e8 LLD · Key-Value Store: Two deposits, one balance, and one silently vanishes https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--lost-update/video.mp4?v=4cc3398b47e8 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--transactions-as-layers BEGIN, SET, BEGIN, SET, COMMIT, ROLLBACK: what's x? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--transactions-as-layers/poster.jpg?v=92f98723efa1 LLD · Key-Value Store: BEGIN, SET, BEGIN, SET, COMMIT, ROLLBACK: what's x? https://media.himanshukukreja.in/lectures/shorts--low-level-design--lld-22-key-value-store-ttl-transactions--transactions-as-layers/video.mp4?v=92f98723efa1 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-01-billbolt-autopay--biller-goes-dark Your biggest biller goes dark. Do you take the money? https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-01-billbolt-autopay--biller-goes-dark/poster.jpg?v=acefbfd4dcbb Mock interview · Billbolt: Your biggest biller goes dark. Do you take the money? https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-01-billbolt-autopay--biller-goes-dark/video.mp4?v=acefbfd4dcbb 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-01-billbolt-autopay--charged-twice-anyway Every payment had an idempotency key. She was still charged twice. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-01-billbolt-autopay--charged-twice-anyway/poster.jpg?v=3443081ae41c Mock interview · Billbolt: Every payment had an idempotency key. She was still charged twice. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-01-billbolt-autopay--charged-twice-anyway/video.mp4?v=3443081ae41c 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-01-billbolt-autopay--thirty-three-hours AutoPay goes 10×. Why more servers won't help. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-01-billbolt-autopay--thirty-three-hours/poster.jpg?v=263435dded35 Mock interview · Billbolt: AutoPay goes 10×. Why more servers won't help. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-01-billbolt-autopay--thirty-three-hours/video.mp4?v=263435dded35 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-02-wanderstay-bookings--charged-no-room The guest paid. The room went to someone else. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-02-wanderstay-bookings--charged-no-room/poster.jpg?v=0d47cfb79e85 Mock interview · Wanderstay: The guest paid. The room went to someone else. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-02-wanderstay-bookings--charged-no-room/video.mp4?v=0d47cfb79e85 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-02-wanderstay-bookings--last-write-wins Why you can't prevent overbooking, only shrink it https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-02-wanderstay-bookings--last-write-wins/poster.jpg?v=5ce7108adc28 Mock interview · Wanderstay: Why you can't prevent overbooking, only shrink it https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-02-wanderstay-bookings--last-write-wins/video.mp4?v=5ce7108adc28 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-03-kaamkaaj-job-search--dashboard-is-wrong The dashboard says 1,340 applies. The inbox says 1,120. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-03-kaamkaaj-job-search--dashboard-is-wrong/poster.jpg?v=bb4a5d85c5c8 Mock interview · Kaamkaaj: The dashboard says 1,340 applies. The inbox says 1,120. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-03-kaamkaaj-job-search--dashboard-is-wrong/video.mp4?v=bb4a5d85c5c8 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-03-kaamkaaj-job-search--forty-matches-one-push 40 matching jobs. How many pushes? https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-03-kaamkaaj-job-search--forty-matches-one-push/poster.jpg?v=38c17df29cf5 Mock interview · Kaamkaaj: 40 matching jobs. How many pushes? https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-03-kaamkaaj-job-search--forty-matches-one-push/video.mp4?v=38c17df29cf5 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-04-tillsy-pos-platform--delete-me Delete my data. But tax law says keep the invoice. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-04-tillsy-pos-platform--delete-me/poster.jpg?v=3eabcefa09da Mock interview · Tillsy: Delete my data. But tax law says keep the invoice. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-04-tillsy-pos-platform--delete-me/video.mp4?v=3eabcefa09da 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-04-tillsy-pos-platform--diwali-wrong-canary Diwali, 7:40 pm: 4% of tills can't sync https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-04-tillsy-pos-platform--diwali-wrong-canary/poster.jpg?v=60c167a91e6e Mock interview · Tillsy: Diwali, 7:40 pm: 4% of tills can't sync https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-04-tillsy-pos-platform--diwali-wrong-canary/video.mp4?v=60c167a91e6e 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-04-tillsy-pos-platform--sales-said-yes Sales already promised dedicated infrastructure. Do you say yes? https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-04-tillsy-pos-platform--sales-said-yes/poster.jpg?v=2e744d1276e7 Mock interview · Tillsy: Sales already promised dedicated infrastructure. Do you say yes? https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-04-tillsy-pos-platform--sales-said-yes/video.mp4?v=2e744d1276e7 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-05-paisly-otp-login--accepted-not-delivered The SMS provider says 200 OK. The login codes never arrive. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-05-paisly-otp-login--accepted-not-delivered/poster.jpg?v=44b516e528f7 Mock interview · Paisly: The SMS provider says 200 OK. The login codes never arrive. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-05-paisly-otp-login--accepted-not-delivered/video.mp4?v=44b516e528f7 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-05-paisly-otp-login--right-code-rejected You typed the right OTP. It said invalid. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-05-paisly-otp-login--right-code-rejected/poster.jpg?v=2ff985186f87 Mock interview · Paisly: You typed the right OTP. It said invalid. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-05-paisly-otp-login--right-code-rejected/video.mp4?v=2ff985186f87 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-05-paisly-otp-login--seven-day-sessions Security wants 7-day sessions. Here's the bill. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-05-paisly-otp-login--seven-day-sessions/poster.jpg?v=6133ce013def Mock interview · Paisly: Security wants 7-day sessions. Here's the bill. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-05-paisly-otp-login--seven-day-sessions/video.mp4?v=6133ce013def 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-06-cartwala-flash-sale-catalog--noon-non-event Last year they flushed the cache at noon. 9 minutes down. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-06-cartwala-flash-sale-catalog--noon-non-event/poster.jpg?v=80e8098ea4c8 Mock interview · Cartwala: Last year they flushed the cache at noon. 9 minutes down. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-06-cartwala-flash-sale-catalog--noon-non-event/video.mp4?v=80e8098ea4c8 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-06-cartwala-flash-sale-catalog--the-4999-laptop A ₹49,999 laptop went live at ₹4,999 https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-06-cartwala-flash-sale-catalog--the-4999-laptop/poster.jpg?v=a63df23ba814 Mock interview · Cartwala: A ₹49,999 laptop went live at ₹4,999 https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-06-cartwala-flash-sale-catalog--the-4999-laptop/video.mp4?v=a63df23ba814 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-07-sunwaai-support-desk--complaint-storm 200,000 tickets in an hour. 400 agents. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-07-sunwaai-support-desk--complaint-storm/poster.jpg?v=c52012582be2 Mock interview · Sunwaai: 200,000 tickets in an hour. 400 agents. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-07-sunwaai-support-desk--complaint-storm/video.mp4?v=c52012582be2 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-07-sunwaai-support-desk--snippet-leak Search showed her a ticket she wasn't allowed to open https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-07-sunwaai-support-desk--snippet-leak/poster.jpg?v=96342934a72e Mock interview · Sunwaai: Search showed her a ticket she wasn't allowed to open https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-07-sunwaai-support-desk--snippet-leak/video.mp4?v=96342934a72e 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-08-switchyard-feature-flags--empty-ruleset-200 The API said 200 OK and sent zero flags https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-08-switchyard-feature-flags--empty-ruleset-200/poster.jpg?v=43f5bac55c07 Mock interview · Switchyard: The API said 200 OK and sent zero flags https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-08-switchyard-feature-flags--empty-ruleset-200/video.mp4?v=43f5bac55c07 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-08-switchyard-feature-flags--kill-switch-proof 2:07 am: a kill switch in 5 seconds, with proof https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-08-switchyard-feature-flags--kill-switch-proof/poster.jpg?v=3f5ce2a91dab Mock interview · Switchyard: 2:07 am: a kill switch in 5 seconds, with proof https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-08-switchyard-feature-flags--kill-switch-proof/video.mp4?v=3f5ce2a91dab 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--mock-interviews--mock-08-switchyard-feature-flags--twenty-sigma-split 510,000 vs 490,000 looks like noise. It's 20 standard deviations. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-08-switchyard-feature-flags--twenty-sigma-split/poster.jpg?v=0e1daec4ab2b Mock interview · Switchyard: 510,000 vs 490,000 looks like noise. It's 20 standard deviations. https://media.himanshukukreja.in/lectures/shorts--mock-interviews--mock-08-switchyard-feature-flags--twenty-sigma-split/video.mp4?v=0e1daec4ab2b 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-01-url-shortener--302-not-301 A 301 would save your short links traffic. Pick 302 anyway. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-01-url-shortener--302-not-301/poster.jpg?v=abc7e2bc50fe Interview problem · URL shortener: A 301 would save your short links traffic. Pick 302 anyway. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-01-url-shortener--302-not-301/video.mp4?v=abc7e2bc50fe 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-01-url-shortener--lease-a-block Two servers, the same millisecond: who gets which short code? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-01-url-shortener--lease-a-block/poster.jpg?v=09a5e78f2c58 Interview problem · URL shortener: Two servers, the same millisecond: who gets which short code? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-01-url-shortener--lease-a-block/video.mp4?v=09a5e78f2c58 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-01-url-shortener--seven-characters Six characters fit every link. So why use seven? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-01-url-shortener--seven-characters/poster.jpg?v=1715ed9eb6e9 Interview problem · URL shortener: Six characters fit every link. So why use seven? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-01-url-shortener--seven-characters/video.mp4?v=1715ed9eb6e9 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-02-rate-limiter--fail-open Redis is down. Does your rate limiter block every request? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-02-rate-limiter--fail-open/poster.jpg?v=9908f3f6f2fd Interview problem · Rate limiter: Redis is down. Does your rate limiter block every request? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-02-rate-limiter--fail-open/video.mp4?v=9908f3f6f2fd 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-02-rate-limiter--noisy-client One client is already over its limit. It's still melting your Redis. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-02-rate-limiter--noisy-client/poster.jpg?v=e0cd49369c62 Interview problem · Rate limiter: One client is already over its limit. It's still melting your Redis. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-02-rate-limiter--noisy-client/video.mp4?v=e0cd49369c62 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-03-key-value-store--deleted-comes-back You deleted the key. Then it came back. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--deleted-comes-back/poster.jpg?v=7566cbca36bc Interview problem · Key-value store: You deleted the key. Then it came back. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--deleted-comes-back/video.mp4?v=7566cbca36bc 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-03-key-value-store--hinted-handoff One replica is down. The cart still takes your write. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--hinted-handoff/poster.jpg?v=c4683da4e0b8 Interview problem · Key-value store: One replica is down. The cart still takes your write. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--hinted-handoff/video.mp4?v=c4683da4e0b8 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-03-key-value-store--replicas-multiply-work 200,000 requests a second. Your cluster does 500,000. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--replicas-multiply-work/poster.jpg?v=b3961bac4d56 Interview problem · Key-value store: 200,000 requests a second. Your cluster does 500,000. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--replicas-multiply-work/video.mp4?v=b3961bac4d56 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-03-key-value-store--two-phones-one-cart Two phones add to one cart at once. Which item survives? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--two-phones-one-cart/poster.jpg?v=656d23b1899e Interview problem · Key-value store: Two phones add to one cart at once. Which item survives? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-03-key-value-store--two-phones-one-cart/video.mp4?v=656d23b1899e 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-04-unique-id-generator--browser-rounds-ids Your server sent one order ID. The browser showed another. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-04-unique-id-generator--browser-rounds-ids/poster.jpg?v=5ff20174f743 Interview problem · Unique ID generator: Your server sent one order ID. The browser showed another. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-04-unique-id-generator--browser-rounds-ids/video.mp4?v=5ff20174f743 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-04-unique-id-generator--sixty-four-bits A million unique IDs a second, and nobody asks anybody https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-04-unique-id-generator--sixty-four-bits/poster.jpg?v=556071c98d9c Interview problem · Unique ID generator: A million unique IDs a second, and nobody asks anybody https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-04-unique-id-generator--sixty-four-bits/video.mp4?v=556071c98d9c 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-04-unique-id-generator--two-worker-17s The ID layout can't collide on paper. Production found two ways. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-04-unique-id-generator--two-worker-17s/poster.jpg?v=3ecd6b5579e8 Interview problem · Unique ID generator: The ID layout can't collide on paper. Production found two ways. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-04-unique-id-generator--two-worker-17s/video.mp4?v=3ecd6b5579e8 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-05-web-crawler--bloom-filter-seen 10 billion URLs remembered in 12 GB, by choosing how to be wrong https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--bloom-filter-seen/poster.jpg?v=445b2bc3fb86 Interview problem · Web crawler: 10 billion URLs remembered in 12 GB, by choosing how to be wrong https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--bloom-filter-seen/video.mp4?v=445b2bc3fb86 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-05-web-crawler--one-host-at-a-time A million URLs from one site: how a crawler stays fast and polite https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--one-host-at-a-time/poster.jpg?v=36830e67122f Interview problem · Web crawler: A million URLs from one site: how a crawler stays fast and polite https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--one-host-at-a-time/video.mp4?v=36830e67122f 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-05-web-crawler--robots-404-vs-503 robots.txt says 404: crawl it all. 503: crawl nothing. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--robots-404-vs-503/poster.jpg?v=7b3d3bdf272f Interview problem · Web crawler: robots.txt says 404: crawl it all. 503: crawl nothing. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--robots-404-vs-503/video.mp4?v=7b3d3bdf272f 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-05-web-crawler--spider-traps This website never ends, and it breaks no rules https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--spider-traps/poster.jpg?v=702724269186 Interview problem · Web crawler: This website never ends, and it breaks no rules https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-05-web-crawler--spider-traps/video.mp4?v=702724269186 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-06-notification-system--otp-behind-the-sale 50 million sale messages, then your login code. Who goes first? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-06-notification-system--otp-behind-the-sale/poster.jpg?v=6d46a9e43b35 Interview problem · Notification system: 50 million sale messages, then your login code. Who goes first? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-06-notification-system--otp-behind-the-sale/video.mp4?v=6d46a9e43b35 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-06-notification-system--the-second-sms The SMS went out. Then the worker crashed. Two SMS? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-06-notification-system--the-second-sms/poster.jpg?v=3fe57483a451 Interview problem · Notification system: The SMS went out. Then the worker crashed. Two SMS? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-06-notification-system--the-second-sms/video.mp4?v=3fe57483a451 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-07-news-feed--cursor-not-offset Why your feed shows you the same five posts twice https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-07-news-feed--cursor-not-offset/poster.jpg?v=849356e336a0 Interview problem · News feed: Why your feed shows you the same five posts twice https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-07-news-feed--cursor-not-offset/video.mp4?v=849356e336a0 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-08-chat-system--reconnect-storm One deploy, 10 million phones reconnecting at once https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-08-chat-system--reconnect-storm/poster.jpg?v=05c866526808 Interview problem · Chat system: One deploy, 10 million phones reconnecting at once https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-08-chat-system--reconnect-storm/video.mp4?v=05c866526808 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-08-chat-system--where-is-bob 10 million open sockets on 200 servers: which one is Bob on? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-08-chat-system--where-is-bob/poster.jpg?v=747efdd86486 Interview problem · Chat system: 10 million open sockets on 200 servers: which one is Bob on? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-08-chat-system--where-is-bob/video.mp4?v=747efdd86486 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-09-typeahead--count-people-not-searches A bot searches one phrase 100,000 times. Does it become a suggestion? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-09-typeahead--count-people-not-searches/poster.jpg?v=30c48f48a6f7 Interview problem · Typeahead: A bot searches one phrase 100,000 times. Does it become a suggestion? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-09-typeahead--count-people-not-searches/video.mp4?v=30c48f48a6f7 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-09-typeahead--top-ten-at-every-node Ten suggestions before your next keystroke, with nothing computed https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-09-typeahead--top-ten-at-every-node/poster.jpg?v=4a4b3d2cedea Interview problem · Typeahead: Ten suggestions before your next keystroke, with nothing computed https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-09-typeahead--top-ten-at-every-node/video.mp4?v=4a4b3d2cedea 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-10-file-sync--conflicted-copy Your laptop and your phone both edited the file. Who wins? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-10-file-sync--conflicted-copy/poster.jpg?v=ea356874d1fc Interview problem · File sync: Your laptop and your phone both edited the file. Who wins? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-10-file-sync--conflicted-copy/video.mp4?v=ea356874d1fc 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-10-file-sync--dedupe-leaks Your upload finished instantly. That's a privacy leak. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-10-file-sync--dedupe-leaks/poster.jpg?v=f7383b013b85 Interview problem · File sync: Your upload finished instantly. That's a privacy leak. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-10-file-sync--dedupe-leaks/video.mp4?v=f7383b013b85 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-10-file-sync--one-sentence-at-the-start One sentence added to a 100 MB file. Why sync re-uploads all of it. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-10-file-sync--one-sentence-at-the-start/poster.jpg?v=ae6cf24ad3b2 Interview problem · File sync: One sentence added to a 100 MB file. Why sync re-uploads all of it. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-10-file-sync--one-sentence-at-the-start/video.mp4?v=ae6cf24ad3b2 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-11-distributed-cache--add-a-node-outage You added a cache node. The database went down. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-11-distributed-cache--add-a-node-outage/poster.jpg?v=3edb9a43638b Interview problem · Distributed cache: You added a cache node. The database went down. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-11-distributed-cache--add-a-node-outage/video.mp4?v=3edb9a43638b 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-11-distributed-cache--hot-key-local-cache One key gets 10% of all reads. More shards won't save you. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-11-distributed-cache--hot-key-local-cache/poster.jpg?v=fa80a3208e0d Interview problem · Distributed cache: One key gets 10% of all reads. More shards won't save you. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-11-distributed-cache--hot-key-local-cache/video.mp4?v=fa80a3208e0d 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-12-pastebin--burn-after-reading A paste that self-destructs on first view. Two people open it at once. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-12-pastebin--burn-after-reading/poster.jpg?v=5aaecb7cb63c Interview problem · Pastebin: A paste that self-destructs on first view. Two people open it at once. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-12-pastebin--burn-after-reading/video.mp4?v=5aaecb7cb63c 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-12-pastebin--expire-on-time The paste expired. The cleanup job is hours behind. Can anyone read it? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-12-pastebin--expire-on-time/poster.jpg?v=5b656490ad3b Interview problem · Pastebin: The paste expired. The cleanup job is hours behind. Can anyone read it? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-12-pastebin--expire-on-time/video.mp4?v=5b656490ad3b 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-12-pastebin--next-id-next-paste Your unlisted paste is one +1 away from a stranger https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-12-pastebin--next-id-next-paste/poster.jpg?v=245903150855 Interview problem · Pastebin: Your unlisted paste is one +1 away from a stranger https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-12-pastebin--next-id-next-paste/video.mp4?v=245903150855 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-13-proximity-service--copy-dont-shard 200 million businesses, and the search index fits on one server https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-13-proximity-service--copy-dont-shard/poster.jpg?v=edad104109bd Interview problem · Proximity service: 200 million businesses, and the search index fits on one server https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-13-proximity-service--copy-dont-shard/video.mp4?v=edad104109bd 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-13-proximity-service--fifty-metres-apart A cafe 50 metres away, invisible to your nearby search https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-13-proximity-service--fifty-metres-apart/poster.jpg?v=11f2f126746d Interview problem · Proximity service: A cafe 50 metres away, invisible to your nearby search https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-13-proximity-service--fifty-metres-apart/video.mp4?v=11f2f126746d 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-14-leaderboard--exact-for-whom Rank 31,402,117 or 31,402,118? Nobody can tell. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-14-leaderboard--exact-for-whom/poster.jpg?v=1985e835ee01 Interview problem · Leaderboard: Rank 31,402,117 or 31,402,118? Nobody can tell. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-14-leaderboard--exact-for-whom/video.mp4?v=1985e835ee01 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-14-leaderboard--rank-is-a-count Your rank, 48,213 of 50 million: why SQL can't answer it live https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-14-leaderboard--rank-is-a-count/poster.jpg?v=b7260d56dc5a Interview problem · Leaderboard: Your rank, 48,213 of 50 million: why SQL can't answer it live https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-14-leaderboard--rank-is-a-count/video.mp4?v=b7260d56dc5a 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-14-leaderboard--ties-in-one-float Two players on 2,210 points. Who ranks higher? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-14-leaderboard--ties-in-one-float/poster.jpg?v=da206770d214 Interview problem · Leaderboard: Two players on 2,210 points. Who ranks higher? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-14-leaderboard--ties-in-one-float/video.mp4?v=da206770d214 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-15-metrics-monitoring--bytes-per-point 16 bytes a point, squeezed to 1.5. Nothing lost. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--bytes-per-point/poster.jpg?v=4b632103a581 Interview problem · Metrics monitoring: 16 bytes a point, squeezed to 1.5. Nothing lost. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--bytes-per-point/video.mp4?v=4b632103a581 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-15-metrics-monitoring--keep-the-max The hour looked calm. It hid a 30-second outage. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--keep-the-max/poster.jpg?v=93aad9631204 Interview problem · Metrics monitoring: The hour looked calm. It hid a 30-second outage. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--keep-the-max/video.mp4?v=93aad9631204 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-15-metrics-monitoring--user-id-label One label on one metric ran the monitoring out of memory https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--user-id-label/poster.jpg?v=86db709ae757 Interview problem · Metrics monitoring: One label on one metric ran the monitoring out of memory https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--user-id-label/video.mp4?v=86db709ae757 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-15-metrics-monitoring--watch-the-watcher Your monitoring dies at 3 a.m. Who tells you? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--watch-the-watcher/poster.jpg?v=95086b6c1a91 Interview problem · Metrics monitoring: Your monitoring dies at 3 a.m. Who tells you? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-15-metrics-monitoring--watch-the-watcher/video.mp4?v=95086b6c1a91 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-16-ad-click-aggregation--four-ways-to-double One ad click, four chances to bill it twice https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-16-ad-click-aggregation--four-ways-to-double/poster.jpg?v=8ada7cc5c830 Interview problem · Ad click aggregation: One ad click, four chances to bill it twice https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-16-ad-click-aggregation--four-ways-to-double/video.mp4?v=8ada7cc5c830 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-16-ad-click-aggregation--the-tunnel-click Clicked at 10:00. Arrived at 10:04. Which minute counts it? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-16-ad-click-aggregation--the-tunnel-click/poster.jpg?v=93a17a85a0ee Interview problem · Ad click aggregation: Clicked at 10:00. Arrived at 10:04. Which minute counts it? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-16-ad-click-aggregation--the-tunnel-click/video.mp4?v=93a17a85a0ee 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-17-job-scheduler--the-missed-run The scheduler was down at 2 a.m. Did the invoices run? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-17-job-scheduler--the-missed-run/poster.jpg?v=e1796f66081c Interview problem · Job scheduler: The scheduler was down at 2 a.m. Did the invoices run? https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-17-job-scheduler--the-missed-run/video.mp4?v=e1796f66081c 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-17-job-scheduler--the-zombie-worker The worker froze mid-job. Then it woke up. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-17-job-scheduler--the-zombie-worker/poster.jpg?v=04c37f03113c Interview problem · Job scheduler: The worker froze mid-job. Then it woke up. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-17-job-scheduler--the-zombie-worker/video.mp4?v=04c37f03113c 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-17-job-scheduler--top-of-the-hour Every hour, on the hour, the scheduler gets hit ten times harder https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-17-job-scheduler--top-of-the-hour/poster.jpg?v=d5ab2c6a0404 Interview problem · Job scheduler: Every hour, on the hour, the scheduler gets hit ten times harder https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-17-job-scheduler--top-of-the-hour/video.mp4?v=d5ab2c6a0404 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-18-message-queue--storage-sets-brokers A million messages a second, and speed isn't the hard part https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-18-message-queue--storage-sets-brokers/poster.jpg?v=6dafc092f11f Interview problem · Message queue: A million messages a second, and speed isn't the hard part https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-18-message-queue--storage-sets-brokers/video.mp4?v=6dafc092f11f 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-18-message-queue--the-seven-day-cliff Your consumer is slow. Nothing is lost. Until day 7. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-18-message-queue--the-seven-day-cliff/poster.jpg?v=e7d92775111a Interview problem · Message queue: Your consumer is slow. Nothing is lost. Until day 7. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-18-message-queue--the-seven-day-cliff/video.mp4?v=e7d92775111a 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-18-message-queue--what-acked-means The broker said got it. Then its disk died. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-18-message-queue--what-acked-means/poster.jpg?v=711fed2d741f Interview problem · Message queue: The broker said got it. Then its disk died. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-18-message-queue--what-acked-means/video.mp4?v=711fed2d741f 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-19-hotel-reservation--one-database-is-enough 5,000 hotels, a million rooms, one booking database https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-19-hotel-reservation--one-database-is-enough/poster.jpg?v=53c1b9d823f4 Interview problem · Hotel reservation: 5,000 hotels, a million rooms, one booking database https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-19-hotel-reservation--one-database-is-enough/video.mp4?v=53c1b9d823f4 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-19-hotel-reservation--the-last-room Two guests, one last room, and both got it https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-19-hotel-reservation--the-last-room/poster.jpg?v=077b3e13bff3 Interview problem · Hotel reservation: Two guests, one last room, and both got it https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-19-hotel-reservation--the-last-room/video.mp4?v=077b3e13bff3 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--problem-bank--problem-20-payment-system--double-entry-ledger One line of code moves the money. Nobody can say why it's wrong. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-20-payment-system--double-entry-ledger/poster.jpg?v=d481165588e7 Interview problem · Payment system: One line of code moves the money. Nobody can say why it's wrong. https://media.himanshukukreja.in/lectures/shorts--problem-bank--problem-20-payment-system--double-entry-ledger/video.mp4?v=d481165588e7 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--37signals-leaves-the-cloud--cloud-exit-math They paid Amazon $3.2 million a year. Then they left. https://media.himanshukukreja.in/lectures/shorts--war-stories--37signals-leaves-the-cloud--cloud-exit-math/poster.jpg?v=5757f04f7af5 War story · 37signals · 2023: They paid Amazon $3.2 million a year. Then they left. https://media.himanshukukreja.in/lectures/shorts--war-stories--37signals-leaves-the-cloud--cloud-exit-math/video.mp4?v=5757f04f7af5 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--ariane-5-sixteen-bit-overflow--sixteen-bits Ariane 5 exploded because one number didn't fit in 16 bits https://media.himanshukukreja.in/lectures/shorts--war-stories--ariane-5-sixteen-bit-overflow--sixteen-bits/poster.jpg?v=b492499d0698 War story · Ariane 5 · 1996: Ariane 5 exploded because one number didn't fit in 16 bits https://media.himanshukukreja.in/lectures/shorts--war-stories--ariane-5-sixteen-bit-overflow--sixteen-bits/video.mp4?v=b492499d0698 94 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--atlassian-775-customers-deleted--site-or-app A cleanup script deleted 883 Atlassian sites in 23 minutes https://media.himanshukukreja.in/lectures/shorts--war-stories--atlassian-775-customers-deleted--site-or-app/poster.jpg?v=eab36536378d War story · Atlassian · 2022: A cleanup script deleted 883 Atlassian sites in 23 minutes https://media.himanshukukreja.in/lectures/shorts--war-stories--atlassian-775-customers-deleted--site-or-app/video.mp4?v=eab36536378d 109 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--att-1990-switch-reset-cascade--the-comeback-crash One switch came back online and jammed AT&T's network for nine hours https://media.himanshukukreja.in/lectures/shorts--war-stories--att-1990-switch-reset-cascade--the-comeback-crash/poster.jpg?v=6656891ec094 War story · AT&T · 1990: One switch came back online and jammed AT&T's network for nine hours https://media.himanshukukreja.in/lectures/shorts--war-stories--att-1990-switch-reset-cascade--the-comeback-crash/video.mp4?v=6656891ec094 99 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--aws-dynamodb-metadata-timeout--answers-too-big A network blip pushed DynamoDB's errors to 55% https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-dynamodb-metadata-timeout--answers-too-big/poster.jpg?v=9cf4c4524c8f War story · AWS · 2015: A network blip pushed DynamoDB's errors to 55% https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-dynamodb-metadata-timeout--answers-too-big/video.mp4?v=9cf4c4524c8f 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--aws-ebs-remirroring-storm--everyone-heals-at-once One misrouted network change froze AWS disks for days https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-ebs-remirroring-storm--everyone-heals-at-once/poster.jpg?v=3754f7ec1415 War story · AWS · 2011: One misrouted network change froze AWS disks for days https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-ebs-remirroring-storm--everyone-heals-at-once/video.mp4?v=3754f7ec1415 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--aws-internal-network-retry-storm--blind-in-the-jam AWS's internal network jammed, and took its own monitoring with it https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-internal-network-retry-storm--blind-in-the-jam/poster.jpg?v=4ad0567aede4 War story · AWS · 2021: AWS's internal network jammed, and took its own monitoring with it https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-internal-network-retry-storm--blind-in-the-jam/video.mp4?v=4ad0567aede4 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--aws-kinesis-thread-limit--one-thread-too-many AWS added a few servers. Kinesis broke for most of a day. https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-kinesis-thread-limit--one-thread-too-many/poster.jpg?v=fffca2f10a0b War story · AWS · 2020: AWS added a few servers. Kinesis broke for most of a day. https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-kinesis-thread-limit--one-thread-too-many/video.mp4?v=fffca2f10a0b 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--aws-s3-one-wrong-input--tools-that-refuse One wrong input took Amazon S3 down for hours https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-s3-one-wrong-input--tools-that-refuse/poster.jpg?v=73b507362222 War story · AWS · 2017: One wrong input took Amazon S3 down for hours https://media.himanshukukreja.in/lectures/shorts--war-stories--aws-s3-one-wrong-input--tools-that-refuse/video.mp4?v=73b507362222 98 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--azure-leap-day-certificate--leap-day-self-healing Adding 1 to the year broke Windows Azure on leap day https://media.himanshukukreja.in/lectures/shorts--war-stories--azure-leap-day-certificate--leap-day-self-healing/poster.jpg?v=1cec1a127a88 War story · Windows Azure · 2012: Adding 1 to the year broke Windows Azure on leap day https://media.himanshukukreja.in/lectures/shorts--war-stories--azure-leap-day-certificate--leap-day-self-healing/video.mp4?v=1cec1a127a88 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--azure-one-router-command--one-router-every-router One command on one router shook Microsoft's whole global network https://media.himanshukukreja.in/lectures/shorts--war-stories--azure-one-router-command--one-router-every-router/poster.jpg?v=ead21ee76561 War story · Microsoft · 2023: One command on one router shook Microsoft's whole global network https://media.himanshukukreja.in/lectures/shorts--war-stories--azure-one-router-command--one-router-every-router/video.mp4?v=ead21ee76561 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--boeing-787-248-days--turn-it-off-and-on A Boeing 787 powered on for 248 days could lose all AC power https://media.himanshukukreja.in/lectures/shorts--war-stories--boeing-787-248-days--turn-it-off-and-on/poster.jpg?v=79586441acda War story · Boeing · 2015: A Boeing 787 powered on for 248 days could lose all AC power https://media.himanshukukreja.in/lectures/shorts--war-stories--boeing-787-248-days--turn-it-off-and-on/video.mp4?v=79586441acda 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--capital-one-firewall-role-buckets--three-commands A misconfigured firewall let an outsider copy Capital One data on about 106 million people https://media.himanshukukreja.in/lectures/shorts--war-stories--capital-one-firewall-role-buckets--three-commands/poster.jpg?v=df8a1a1b22a7 War story · Capital One · 2019: A misconfigured firewall let an outsider copy Capital One data on about 106 million people https://media.himanshukukreja.in/lectures/shorts--war-stories--capital-one-firewall-role-buckets--three-commands/video.mp4?v=df8a1a1b22a7 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--centurylink-four-malformed-packets--packets-that-never-die Four packets that never expired took down CenturyLink, and 911, for 37 hours https://media.himanshukukreja.in/lectures/shorts--war-stories--centurylink-four-malformed-packets--packets-that-never-die/poster.jpg?v=9fbc28e51095 War story · CenturyLink · 2018: Four packets that never expired took down CenturyLink, and 911, for 37 hours https://media.himanshukukreja.in/lectures/shorts--war-stories--centurylink-four-malformed-packets--packets-that-never-die/video.mp4?v=9fbc28e51095 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--cloudbleed-one-equals-sign--one-character Cloudbleed: == instead of >= made Cloudflare leak private data https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudbleed-one-equals-sign--one-character/poster.jpg?v=5de856ac7afc War story · Cloudflare · 2017: Cloudbleed: == instead of >= made Cloudflare leak private data https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudbleed-one-equals-sign--one-character/video.mp4?v=5de856ac7afc 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--cloudflare-one-regex--catastrophic-backtracking One line of regex knocked Cloudflare offline https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudflare-one-regex--catastrophic-backtracking/poster.jpg?v=203b2130122f War story · Cloudflare · 2019: One line of regex knocked Cloudflare offline https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudflare-one-regex--catastrophic-backtracking/video.mp4?v=203b2130122f 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--cloudflare-portland-power-failure--never-tested-the-whole-building Cloudflare could survive losing a data center. Except the one it never tested. https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudflare-portland-power-failure--never-tested-the-whole-building/poster.jpg?v=a59af0d7e916 War story · Cloudflare · 2023: Cloudflare could survive losing a data center. Except the one it never tested. https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudflare-portland-power-failure--never-tested-the-whole-building/video.mp4?v=a59af0d7e916 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--cloudflare-reject-the-rest--order-is-logic Two rules moved below REJECT-THE-REST. Cloudflare lost 19 data centers. https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudflare-reject-the-rest--order-is-logic/poster.jpg?v=6e49846ebc47 War story · Cloudflare · 2022: Two rules moved below REJECT-THE-REST. Cloudflare lost 19 data centers. https://media.himanshukukreja.in/lectures/shorts--war-stories--cloudflare-reject-the-rest--order-is-logic/video.mp4?v=6e49846ebc47 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--code-spaces-one-control-panel--deleted-in-12-hours An attacker deleted Code Spaces' servers and backups in 12 hours, and the company shut down https://media.himanshukukreja.in/lectures/shorts--war-stories--code-spaces-one-control-panel--deleted-in-12-hours/poster.jpg?v=937f6a6be76f War story · Code Spaces · 2014: An attacker deleted Code Spaces' servers and backups in 12 hours, and the company shut down https://media.himanshukukreja.in/lectures/shorts--war-stories--code-spaces-one-control-panel--deleted-in-12-hours/video.mp4?v=937f6a6be76f 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--cowin-registration-opening-day--the-real-bottleneck CoWIN took 383 million hits. Most people still couldn't book. https://media.himanshukukreja.in/lectures/shorts--war-stories--cowin-registration-opening-day--the-real-bottleneck/poster.jpg?v=20a3039d76d6 War story · CoWIN · 2021: CoWIN took 383 million hits. Most people still couldn't book. https://media.himanshukukreja.in/lectures/shorts--war-stories--cowin-registration-opening-day--the-real-bottleneck/video.mp4?v=20a3039d76d6 93 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--crowdstrike-one-content-update--the-21st-field One CrowdStrike content update crashed an estimated 8.5 million Windows computers https://media.himanshukukreja.in/lectures/shorts--war-stories--crowdstrike-one-content-update--the-21st-field/poster.jpg?v=1d40eeecf9e8 War story · CrowdStrike · 2024: One CrowdStrike content update crashed an estimated 8.5 million Windows computers https://media.himanshukukreja.in/lectures/shorts--war-stories--crowdstrike-one-content-update--the-21st-field/video.mp4?v=1d40eeecf9e8 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--datadog-same-hour-every-region--the-hidden-clock Five independent regions. One update. Same hour. All down. https://media.himanshukukreja.in/lectures/shorts--war-stories--datadog-same-hour-every-region--the-hidden-clock/poster.jpg?v=7a38b75097a6 War story · Datadog · 2023: Five independent regions. One update. Same hour. All down. https://media.himanshukukreja.in/lectures/shorts--war-stories--datadog-same-hour-every-region--the-hidden-clock/video.mp4?v=7a38b75097a6 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--discord-trillions-of-messages--nine-day-copy Three months, said the tool. The rewrite said nine days. https://media.himanshukukreja.in/lectures/shorts--war-stories--discord-trillions-of-messages--nine-day-copy/poster.jpg?v=d76c022d4346 War story · Discord · 2022: Three months, said the tool. The rewrite said nine days. https://media.himanshukukreja.in/lectures/shorts--war-stories--discord-trillions-of-messages--nine-day-copy/video.mp4?v=d76c022d4346 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--dropbox-magic-pocket--base-jump Dropbox moved 500 petabytes off Amazon in a sprint called BASE Jump https://media.himanshukukreja.in/lectures/shorts--war-stories--dropbox-magic-pocket--base-jump/poster.jpg?v=d590bea14cea War story · Dropbox · 2015: Dropbox moved 500 petabytes off Amazon in a sprint called BASE Jump https://media.himanshukukreja.in/lectures/shorts--war-stories--dropbox-magic-pocket--base-jump/video.mp4?v=d590bea14cea 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--dropbox-upgrade-script-live-databases--the-check-that-failed Dropbox's upgrade script had one job: skip live machines. https://media.himanshukukreja.in/lectures/shorts--war-stories--dropbox-upgrade-script-live-databases--the-check-that-failed/poster.jpg?v=7774d3af7452 War story · Dropbox · 2014: Dropbox's upgrade script had one job: skip live machines. https://media.himanshukukreja.in/lectures/shorts--war-stories--dropbox-upgrade-script-live-databases--the-check-that-failed/video.mp4?v=7774d3af7452 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--equifax-expired-inspection-certificate--the-blind-guard Equifax's breach went unseen for 76 days because a traffic-inspection certificate had expired https://media.himanshukukreja.in/lectures/shorts--war-stories--equifax-expired-inspection-certificate--the-blind-guard/poster.jpg?v=96726dc1b7b8 War story · Equifax · 2017: Equifax's breach went unseen for 76 days because a traffic-inspection certificate had expired https://media.himanshukukreja.in/lectures/shorts--war-stories--equifax-expired-inspection-certificate--the-blind-guard/video.mp4?v=96726dc1b7b8 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--ericsson-one-certificate-eleven-countries--nine-month-timer One expired certificate cut mobile data in 11 countries at once https://media.himanshukukreja.in/lectures/shorts--war-stories--ericsson-one-certificate-eleven-countries--nine-month-timer/poster.jpg?v=6fa26801bb28 War story · Ericsson · 2018: One expired certificate cut mobile data in 11 countries at once https://media.himanshukukreja.in/lectures/shorts--war-stories--ericsson-one-certificate-eleven-countries--nine-month-timer/video.mp4?v=6fa26801bb28 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--exchange-y2k22-date-overflow--december-33rd Microsoft Exchange stopped delivering email on 1 January 2022 https://media.himanshukukreja.in/lectures/shorts--war-stories--exchange-y2k22-date-overflow--december-33rd/poster.jpg?v=f3c9936fa9ea War story · Microsoft · 2022: Microsoft Exchange stopped delivering email on 1 January 2022 https://media.himanshukukreja.in/lectures/shorts--war-stories--exchange-y2k22-date-overflow--december-33rd/video.mp4?v=f3c9936fa9ea 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--faa-notam-backup-synced--backup-copied-the-damage The FAA paused every US departure after files were deleted while fixing a database sync https://media.himanshukukreja.in/lectures/shorts--war-stories--faa-notam-backup-synced--backup-copied-the-damage/poster.jpg?v=e50fadd4ed3f War story · US FAA · 2023: The FAA paused every US departure after files were deleted while fixing a database sync https://media.himanshukukreja.in/lectures/shorts--war-stories--faa-notam-backup-synced--backup-copied-the-damage/video.mp4?v=e50fadd4ed3f 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--facebook-bgp-six-hours--locked-out One command took Facebook off the internet, and locked its engineers out https://media.himanshukukreja.in/lectures/shorts--war-stories--facebook-bgp-six-hours--locked-out/poster.jpg?v=d3d714a13b36 War story · Facebook · 2021: One command took Facebook off the internet, and locked its engineers out https://media.himanshukukreja.in/lectures/shorts--war-stories--facebook-bgp-six-hours--locked-out/video.mp4?v=d3d714a13b36 104 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--fastly-one-customer-config--one-valid-setting One customer's valid setting broke 85% of Fastly https://media.himanshukukreja.in/lectures/shorts--war-stories--fastly-one-customer-config--one-valid-setting/poster.jpg?v=6a61f5688bfd War story · Fastly · 2021: One customer's valid setting broke 85% of Fastly https://media.himanshukukreja.in/lectures/shorts--war-stories--fastly-one-customer-config--one-valid-setting/video.mp4?v=6a61f5688bfd 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--flash-crash-volume-only-algorithm--sell-with-the-volume The 2010 Flash Crash: an algorithm that sold faster the more trading it helped cause https://media.himanshukukreja.in/lectures/shorts--war-stories--flash-crash-volume-only-algorithm--sell-with-the-volume/poster.jpg?v=35ec410e6d79 War story · Flash Crash · 2010: The 2010 Flash Crash: an algorithm that sold faster the more trading it helped cause https://media.himanshukukreja.in/lectures/shorts--war-stories--flash-crash-volume-only-algorithm--sell-with-the-volume/video.mp4?v=35ec410e6d79 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--flipkart-big-billion-day-apology--twenty-x-not-enough Flipkart planned for 20x traffic and still fell over https://media.himanshukukreja.in/lectures/shorts--war-stories--flipkart-big-billion-day-apology--twenty-x-not-enough/poster.jpg?v=a229141706e3 War story · Flipkart · 2014: Flipkart planned for 20x traffic and still fell over https://media.himanshukukreja.in/lectures/shorts--war-stories--flipkart-big-billion-day-apology--twenty-x-not-enough/video.mp4?v=a229141706e3 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--fortnite-3-4-million-players--the-health-check-trap Fortnite hit 3.4 million players at once, and a 100 ms cache timeout blocked sign-ins https://media.himanshukukreja.in/lectures/shorts--war-stories--fortnite-3-4-million-players--the-health-check-trap/poster.jpg?v=f7f4cb50a7d9 War story · Epic Games · 2018: Fortnite hit 3.4 million players at once, and a 100 ms cache timeout blocked sign-ins https://media.himanshukukreja.in/lectures/shorts--war-stories--fortnite-3-4-million-players--the-health-check-trap/video.mp4?v=f7f4cb50a7d9 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--gangnam-style-view-counter--already-fixed Gangnam Style didn't really break YouTube's view counter https://media.himanshukukreja.in/lectures/shorts--war-stories--gangnam-style-view-counter--already-fixed/poster.jpg?v=cbeddddcbcd5 War story · YouTube · 2014: Gangnam Style didn't really break YouTube's view counter https://media.himanshukukreja.in/lectures/shorts--war-stories--gangnam-style-view-counter--already-fixed/video.mp4?v=cbeddddcbcd5 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--github-43-second-partition--no-way-back A 43-second blip moved GitHub's databases across the country https://media.himanshukukreja.in/lectures/shorts--war-stories--github-43-second-partition--no-way-back/poster.jpg?v=0085816eb3cb War story · GitHub · 2018: A 43-second blip moved GitHub's databases across the country https://media.himanshukukreja.in/lectures/shorts--war-stories--github-43-second-partition--no-way-back/video.mp4?v=0085816eb3cb 113 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--gitlab-database-deletion--untested-backups GitLab wiped its main database. Then it looked for the backups. https://media.himanshukukreja.in/lectures/shorts--war-stories--gitlab-database-deletion--untested-backups/poster.jpg?v=494b616e88e5 War story · GitLab · 2017: GitLab wiped its main database. Then it looked for the backups. https://media.himanshukukreja.in/lectures/shorts--war-stories--gitlab-database-deletion--untested-backups/video.mp4?v=494b616e88e5 96 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--gmail-saved-by-tape--the-copy-offline A bug emptied Gmail inboxes. Tape brought them back. https://media.himanshukukreja.in/lectures/shorts--war-stories--gmail-saved-by-tape--the-copy-offline/poster.jpg?v=e9d111334b5d War story · Google · 2011: A bug emptied Gmail inboxes. Tape brought them back. https://media.himanshukukreja.in/lectures/shorts--war-stories--gmail-saved-by-tape--the-copy-offline/video.mp4?v=e9d111334b5d 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--google-auth-quota-zero--usage-zero Google's sign-in died for 47 minutes because a quota system read zero https://media.himanshukukreja.in/lectures/shorts--war-stories--google-auth-quota-zero--usage-zero/poster.jpg?v=ff538775ca48 War story · Google · 2020: Google's sign-in died for 47 minutes because a quota system read zero https://media.himanshukukreja.in/lectures/shorts--war-stories--google-auth-quota-zero--usage-zero/video.mp4?v=ff538775ca48 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--google-chubby-planned-outage--too-reliable Google takes its Chubby lock service down on purpose when it has been too reliable https://media.himanshukukreja.in/lectures/shorts--war-stories--google-chubby-planned-outage--too-reliable/poster.jpg?v=f32899e98aef War story · Google · 2016: Google takes its Chubby lock service down on purpose when it has been too reliable https://media.himanshukukreja.in/lectures/shorts--war-stories--google-chubby-planned-outage--too-reliable/video.mp4?v=f32899e98aef 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--google-cloud-maintenance-took-the-network--all-copies-at-once A maintenance job switched off Google's network brains in several places at once https://media.himanshukukreja.in/lectures/shorts--war-stories--google-cloud-maintenance-took-the-network--all-copies-at-once/poster.jpg?v=0d8725d948ad War story · Google Cloud · 2019: A maintenance job switched off Google's network brains in several places at once https://media.himanshukukreja.in/lectures/shorts--war-stories--google-cloud-maintenance-took-the-network--all-copies-at-once/video.mp4?v=0d8725d948ad 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--google-flagged-the-whole-web--one-slash One slash made Google flag every website as harmful https://media.himanshukukreja.in/lectures/shorts--war-stories--google-flagged-the-whole-web--one-slash/poster.jpg?v=8ee5646ad96a War story · Google · 2009: One slash made Google flag every website as harmful https://media.himanshukukreja.in/lectures/shorts--war-stories--google-flagged-the-whole-web--one-slash/video.mp4?v=8ee5646ad96a 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--google-lightning-belgium--four-strikes Lightning struck a Google data center's grid four times in a row https://media.himanshukukreja.in/lectures/shorts--war-stories--google-lightning-belgium--four-strikes/poster.jpg?v=e58e03b2ce7d War story · Google Cloud · 2015: Lightning struck a Google data center's grid four times in a row https://media.himanshukukreja.in/lectures/shorts--war-stories--google-lightning-belgium--four-strikes/video.mp4?v=e58e03b2ce7d 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--hdfc-bank-rbi-digital-freeze--no-new-cards The RBI stopped HDFC Bank from signing up new credit card customers over outages https://media.himanshukukreja.in/lectures/shorts--war-stories--hdfc-bank-rbi-digital-freeze--no-new-cards/poster.jpg?v=c6e624ed8f1a War story · HDFC Bank · 2020: The RBI stopped HDFC Bank from signing up new credit card customers over outages https://media.himanshukukreja.in/lectures/shorts--war-stories--hdfc-bank-rbi-digital-freeze--no-new-cards/video.mp4?v=c6e624ed8f1a 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--healthcare-gov-six-on-day-one--one-lane-onramp HealthCare.gov launched to 250,000 people at once, and six signed up on day one https://media.himanshukukreja.in/lectures/shorts--war-stories--healthcare-gov-six-on-day-one--one-lane-onramp/poster.jpg?v=bdc0ce95acb9 War story · HealthCare.gov · 2013: HealthCare.gov launched to 250,000 people at once, and six signed up on day one https://media.himanshukukreja.in/lectures/shorts--war-stories--healthcare-gov-six-on-day-one--one-lane-onramp/video.mp4?v=bdc0ce95acb9 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--jiocinema-ipl-2023-record--free-changes-everything JioCinema made the IPL free. 3.21 crore watched the final at once. https://media.himanshukukreja.in/lectures/shorts--war-stories--jiocinema-ipl-2023-record--free-changes-everything/poster.jpg?v=6fc73afa3081 War story · JioCinema · 2023: JioCinema made the IPL free. 3.21 crore watched the final at once. https://media.himanshukukreja.in/lectures/shorts--war-stories--jiocinema-ipl-2023-record--free-changes-everything/video.mp4?v=6fc73afa3081 98 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--joyent-rebooted-whole-data-center--reboot-all One mistyped command rebooted Joyent's entire data center https://media.himanshukukreja.in/lectures/shorts--war-stories--joyent-rebooted-whole-data-center--reboot-all/poster.jpg?v=0c3baa84380a War story · Joyent · 2014: One mistyped command rebooted Joyent's entire data center https://media.himanshukukreja.in/lectures/shorts--war-stories--joyent-rebooted-whole-data-center--reboot-all/video.mp4?v=0c3baa84380a 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--knight-capital-45-minutes--one-missed-server One server missed a deploy. Knight lost $460 million in 45 minutes. https://media.himanshukukreja.in/lectures/shorts--war-stories--knight-capital-45-minutes--one-missed-server/poster.jpg?v=aaa17c8be36e War story · Knight Capital · 2012: One server missed a deploy. Knight lost $460 million in 45 minutes. https://media.himanshukukreja.in/lectures/shorts--war-stories--knight-capital-45-minutes--one-missed-server/video.mp4?v=aaa17c8be36e 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--leap-second-2012--one-extra-second One extra second jammed Linux servers across the web https://media.himanshukukreja.in/lectures/shorts--war-stories--leap-second-2012--one-extra-second/poster.jpg?v=249629ce5105 War story · Linux · 2012: One extra second jammed Linux servers across the web https://media.himanshukukreja.in/lectures/shorts--war-stories--leap-second-2012--one-extra-second/video.mp4?v=249629ce5105 102 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--left-pad-eleven-lines--one-tiny-dependency Eleven lines of left-pad vanished from npm, and builds broke https://media.himanshukukreja.in/lectures/shorts--war-stories--left-pad-eleven-lines--one-tiny-dependency/poster.jpg?v=9ae97ede1113 War story · npm · 2016: Eleven lines of left-pad vanished from npm, and builds broke https://media.himanshukukreja.in/lectures/shorts--war-stories--left-pad-eleven-lines--one-tiny-dependency/video.mp4?v=9ae97ede1113 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--lets-encrypt-old-root-expires--the-android-loophole Let's Encrypt's old root expired. The fix for old phones was a trap for old OpenSSL. https://media.himanshukukreja.in/lectures/shorts--war-stories--lets-encrypt-old-root-expires--the-android-loophole/poster.jpg?v=cef3973810b6 War story · Let's Encrypt · 2021: Let's Encrypt's old root expired. The fix for old phones was a trap for old OpenSSL. https://media.himanshukukreja.in/lectures/shorts--war-stories--lets-encrypt-old-root-expires--the-android-loophole/video.mp4?v=cef3973810b6 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--mars-climate-orbiter-units--pounds-vs-newtons NASA lost a Mars orbiter to pound-seconds https://media.himanshukukreja.in/lectures/shorts--war-stories--mars-climate-orbiter-units--pounds-vs-newtons/poster.jpg?v=e02deaaaf447 War story · NASA · 1999: NASA lost a Mars orbiter to pound-seconds https://media.himanshukukreja.in/lectures/shorts--war-stories--mars-climate-orbiter-units--pounds-vs-newtons/video.mp4?v=e02deaaaf447 97 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--microsoft-teams-expired-certificate--a-date-you-knew Microsoft Teams went down because a certificate expired https://media.himanshukukreja.in/lectures/shorts--war-stories--microsoft-teams-expired-certificate--a-date-you-knew/poster.jpg?v=177a0844347b War story · Microsoft · 2020: Microsoft Teams went down because a certificate expired https://media.himanshukukreja.in/lectures/shorts--war-stories--microsoft-teams-expired-certificate--a-date-you-knew/video.mp4?v=177a0844347b 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--monzo-empty-servers-answered--six-empty-servers Monzo added six empty servers. They started answering. https://media.himanshukukreja.in/lectures/shorts--war-stories--monzo-empty-servers-answered--six-empty-servers/poster.jpg?v=3f925781a065 War story · Monzo · 2019: Monzo added six empty servers. They started answering. https://media.himanshukukreja.in/lectures/shorts--war-stories--monzo-empty-servers-answered--six-empty-servers/video.mp4?v=3f925781a065 94 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--nats-one-flight-plan--two-places-called-dvl One flight plan with two places called DVL stopped UK air traffic control's flight data https://media.himanshukukreja.in/lectures/shorts--war-stories--nats-one-flight-plan--two-places-called-dvl/poster.jpg?v=7f41c4f3d3f3 War story · NATS · 2023: One flight plan with two places called DVL stopped UK air traffic control's flight data https://media.himanshukukreja.in/lectures/shorts--war-stories--nats-one-flight-plan--two-places-called-dvl/video.mp4?v=7f41c4f3d3f3 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--netflix-rode-out-aws-2011--built-to-lose-a-zone Netflix kept streaming through the April 2011 AWS outage that hampered popular sites https://media.himanshukukreja.in/lectures/shorts--war-stories--netflix-rode-out-aws-2011--built-to-lose-a-zone/poster.jpg?v=b0451c7d0183 War story · Netflix · 2011: Netflix kept streaming through the April 2011 AWS outage that hampered popular sites https://media.himanshukukreja.in/lectures/shorts--war-stories--netflix-rode-out-aws-2011--built-to-lose-a-zone/video.mp4?v=b0451c7d0183 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--netflix-seven-years-to-the-cloud--forklift-or-rebuild Three days without DVDs started Netflix's seven-year rebuild https://media.himanshukukreja.in/lectures/shorts--war-stories--netflix-seven-years-to-the-cloud--forklift-or-rebuild/poster.jpg?v=ff9c1c35cd01 War story · Netflix · 2008: Three days without DVDs started Netflix's seven-year rebuild https://media.himanshukukreja.in/lectures/shorts--war-stories--netflix-seven-years-to-the-cloud--forklift-or-rebuild/video.mp4?v=ff9c1c35cd01 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--northeast-blackout-silent-alarm--silent-alarm The 2003 blackout grew in a control room whose alarms had silently stopped https://media.himanshukukreja.in/lectures/shorts--war-stories--northeast-blackout-silent-alarm--silent-alarm/poster.jpg?v=734fe21e19ae War story · FirstEnergy · 2003: The 2003 blackout grew in a control room whose alarms had silently stopped https://media.himanshukukreja.in/lectures/shorts--war-stories--northeast-blackout-silent-alarm--silent-alarm/video.mp4?v=734fe21e19ae 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--nse-trading-halt-2021--engine-was-fine NSE's trading engine was fine. The market still stopped for four hours. https://media.himanshukukreja.in/lectures/shorts--war-stories--nse-trading-halt-2021--engine-was-fine/poster.jpg?v=4fec5e202998 War story · NSE · 2021: NSE's trading engine was fine. The market still stopped for four hours. https://media.himanshukukreja.in/lectures/shorts--war-stories--nse-trading-halt-2021--engine-was-fine/video.mp4?v=4fec5e202998 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--patriot-missile-clock-drift--hundred-hours A Patriot battery missed a Scud because it had been on for 100 hours https://media.himanshukukreja.in/lectures/shorts--war-stories--patriot-missile-clock-drift--hundred-hours/poster.jpg?v=fea538407f54 War story · Patriot missile · 1991: A Patriot battery missed a Scud because it had been on for 100 hours https://media.himanshukukreja.in/lectures/shorts--war-stories--patriot-missile-clock-drift--hundred-hours/video.mp4?v=fea538407f54 99 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--pokemon-go-fifty-times-the-estimate--engine-swap-mid-flight Pokémon GO planned for 5x. It got 50x. https://media.himanshukukreja.in/lectures/shorts--war-stories--pokemon-go-fifty-times-the-estimate--engine-swap-mid-flight/poster.jpg?v=d96564cbb043 War story · Niantic · 2016: Pokémon GO planned for 5x. It got 50x. https://media.himanshukukreja.in/lectures/shorts--war-stories--pokemon-go-fifty-times-the-estimate--engine-swap-mid-flight/video.mp4?v=d96564cbb043 96 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--prime-video-monitoring-monolith--serverless-to-monolith Prime Video made one tool a monolith and cut its cost 90% https://media.himanshukukreja.in/lectures/shorts--war-stories--prime-video-monitoring-monolith--serverless-to-monolith/poster.jpg?v=e210e7846402 War story · Prime Video · 2023: Prime Video made one tool a monolith and cut its cost 90% https://media.himanshukukreja.in/lectures/shorts--war-stories--prime-video-monitoring-monolith--serverless-to-monolith/video.mp4?v=e210e7846402 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--reddit-pi-day-node-label--the-forgotten-label One renamed label took Reddit down for 314 minutes. https://media.himanshukukreja.in/lectures/shorts--war-stories--reddit-pi-day-node-label--the-forgotten-label/poster.jpg?v=17fe05b95bca War story · Reddit · 2023: One renamed label took Reddit down for 314 minutes. https://media.himanshukukreja.in/lectures/shorts--war-stories--reddit-pi-day-node-label--the-forgotten-label/video.mp4?v=17fe05b95bca 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--robinhood-thundering-herd-dns--worst-day-to-break The market went wild. Robinhood's DNS went down. https://media.himanshukukreja.in/lectures/shorts--war-stories--robinhood-thundering-herd-dns--worst-day-to-break/poster.jpg?v=44998b068307 War story · Robinhood · 2020: The market went wild. Robinhood's DNS went down. https://media.himanshukukreja.in/lectures/shorts--war-stories--robinhood-thundering-herd-dns--worst-day-to-break/video.mp4?v=44998b068307 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--roblox-73-hour-outage--consul-choked Roblox was down for 73 hours because its service directory choked https://media.himanshukukreja.in/lectures/shorts--war-stories--roblox-73-hour-outage--consul-choked/poster.jpg?v=a9deb87f0d16 War story · Roblox · 2021: Roblox was down for 73 hours because its service directory choked https://media.himanshukukreja.in/lectures/shorts--war-stories--roblox-73-hour-outage--consul-choked/video.mp4?v=a9deb87f0d16 101 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--rogers-routing-filter-removed--one-deleted-filter Rogers deleted one routing filter and lost its whole network, 911 included https://media.himanshukukreja.in/lectures/shorts--war-stories--rogers-routing-filter-removed--one-deleted-filter/poster.jpg?v=b9b1e6564536 War story · Rogers · 2022: Rogers deleted one routing filter and lost its whole network, 911 included https://media.himanshukukreja.in/lectures/shorts--war-stories--rogers-routing-filter-removed--one-deleted-filter/video.mp4?v=b9b1e6564536 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--s3-bucket-name-clash-bill--their-traffic-your-bill A test bucket's name cost him $1,300 in a day https://media.himanshukukreja.in/lectures/shorts--war-stories--s3-bucket-name-clash-bill--their-traffic-your-bill/poster.jpg?v=6d2cfb9c1ae9 War story · AWS · 2024: A test bucket's name cost him $1,300 in a day https://media.himanshukukreja.in/lectures/shorts--war-stories--s3-bucket-name-clash-bill--their-traffic-your-bill/video.mp4?v=6d2cfb9c1ae9 101 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--segment-back-to-monolith--140-services-to-one Segment merged over 140 microservices back into one https://media.himanshukukreja.in/lectures/shorts--war-stories--segment-back-to-monolith--140-services-to-one/poster.jpg?v=0808f03664d2 War story · Segment · 2018: Segment merged over 140 microservices back into one https://media.himanshukukreja.in/lectures/shorts--war-stories--segment-back-to-monolith--140-services-to-one/video.mp4?v=0808f03664d2 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--slack-cache-healed-too-fast--too-good-at-its-job Slack's cache manager was too good at its job. https://media.himanshukukreja.in/lectures/shorts--war-stories--slack-cache-healed-too-fast--too-good-at-its-job/poster.jpg?v=83658d8ecd00 War story · Slack · 2022: Slack's cache manager was too good at its job. https://media.himanshukukreja.in/lectures/shorts--war-stories--slack-cache-healed-too-fast--too-good-at-its-job/video.mp4?v=83658d8ecd00 100 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--slack-january-2021-scale-up--autoscaling-speed-limit Slack's first workday of 2021 broke a network hub meant to scale itself https://media.himanshukukreja.in/lectures/shorts--war-stories--slack-january-2021-scale-up--autoscaling-speed-limit/poster.jpg?v=5b2386fd3774 War story · Slack · 2021: Slack's first workday of 2021 broke a network hub meant to scale itself https://media.himanshukukreja.in/lectures/shorts--war-stories--slack-january-2021-scale-up--autoscaling-speed-limit/video.mp4?v=5b2386fd3774 113 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--southwest-crew-scheduling-backlog--where-are-the-crews Southwest cancelled 16,900 flights because crew schedules couldn't keep up with the changes https://media.himanshukukreja.in/lectures/shorts--war-stories--southwest-crew-scheduling-backlog--where-are-the-crews/poster.jpg?v=f843c065061c War story · Southwest Airlines · 2022: Southwest cancelled 16,900 flights because crew schedules couldn't keep up with the changes https://media.himanshukukreja.in/lectures/shorts--war-stories--southwest-crew-scheduling-backlog--where-are-the-crews/video.mp4?v=f843c065061c 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--steam-christmas-cached-accounts--someone-elses-page On Christmas Day, Steam showed you someone else's account. https://media.himanshukukreja.in/lectures/shorts--war-stories--steam-christmas-cached-accounts--someone-elses-page/poster.jpg?v=2cf25dcf1de8 War story · Valve · 2015: On Christmas Day, Steam showed you someone else's account. https://media.himanshukukreja.in/lectures/shorts--war-stories--steam-christmas-cached-accounts--someone-elses-page/video.mp4?v=2cf25dcf1de8 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--stripe-rollback-second-outage--the-fix-broke-it Stripe fixed its outage. Then the fix caused a second one. https://media.himanshukukreja.in/lectures/shorts--war-stories--stripe-rollback-second-outage--the-fix-broke-it/poster.jpg?v=839b5268b391 War story · Stripe · 2019: Stripe fixed its outage. Then the fix caused a second one. https://media.himanshukukreja.in/lectures/shorts--war-stories--stripe-rollback-second-outage--the-fix-broke-it/video.mp4?v=839b5268b391 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--swiggy-new-years-eve-war-room--peak-is-a-project How Swiggy prepares for its busiest night of the year https://media.himanshukukreja.in/lectures/shorts--war-stories--swiggy-new-years-eve-war-room--peak-is-a-project/poster.jpg?v=5a300a4cb73d War story · Swiggy · 2022: How Swiggy prepares for its busiest night of the year https://media.himanshukukreja.in/lectures/shorts--war-stories--swiggy-new-years-eve-war-room--peak-is-a-project/video.mp4?v=5a300a4cb73d 92 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--therac-25-fast-typist-race--eight-seconds The Therac-25 overdosed patients when its operator edited too fast https://media.himanshukukreja.in/lectures/shorts--war-stories--therac-25-fast-typist-race--eight-seconds/poster.jpg?v=4ea3d0c23693 War story · Therac-25 · 1985–1987: The Therac-25 overdosed patients when its operator edited too fast https://media.himanshukukreja.in/lectures/shorts--war-stories--therac-25-fast-typist-race--eight-seconds/video.mp4?v=4ea3d0c23693 96 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--tsb-migration-two-data-centres--the-other-data-centre TSB moved 5.2 million customers to a new platform, and their sessions landed in the wrong data centr https://media.himanshukukreja.in/lectures/shorts--war-stories--tsb-migration-two-data-centres--the-other-data-centre/poster.jpg?v=c031300d62bc War story · TSB Bank · 2018: TSB moved 5.2 million customers to a new platform, and their sessions landed in the wrong data centre https://media.himanshukukreja.in/lectures/shorts--war-stories--tsb-migration-two-data-centres--the-other-data-centre/video.mp4?v=c031300d62bc 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--twilio-redis-recharge-loop--charge-it-again Twilio's balances went read-only. The cards kept getting charged. https://media.himanshukukreja.in/lectures/shorts--war-stories--twilio-redis-recharge-loop--charge-it-again/poster.jpg?v=2527376897e6 War story · Twilio · 2013: Twilio's balances went read-only. The cards kept getting charged. https://media.himanshukukreja.in/lectures/shorts--war-stories--twilio-redis-recharge-loop--charge-it-again/video.mp4?v=2527376897e6 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--whatsapp-two-million-connections--two-million-connections One WhatsApp server held 2 million connections, 42% idle https://media.himanshukukreja.in/lectures/shorts--war-stories--whatsapp-two-million-connections--two-million-connections/poster.jpg?v=4859a4e9a1e4 War story · WhatsApp · 2012: One WhatsApp server held 2 million connections, 42% idle https://media.himanshukukreja.in/lectures/shorts--war-stories--whatsapp-two-million-connections--two-million-connections/video.mp4?v=4859a4e9a1e4 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--zoom-participants-not-users--counted-five-times Zoom's 300 million were participants, not users https://media.himanshukukreja.in/lectures/shorts--war-stories--zoom-participants-not-users--counted-five-times/poster.jpg?v=2963aad86803 War story · Zoom · 2020: Zoom's 300 million were participants, not users https://media.himanshukukreja.in/lectures/shorts--war-stories--zoom-participants-not-users--counted-five-times/video.mp4?v=2963aad86803 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--war-stories--zune-leap-year-freeze--day-366 Zune 30GB players froze on 31 December 2008. The fix was to wait. https://media.himanshukukreja.in/lectures/shorts--war-stories--zune-leap-year-freeze--day-366/poster.jpg?v=36f75189fec1 War story · Microsoft · 2008: Zune 30GB players froze on 31 December 2008. The fix was to wait. https://media.himanshukukreja.in/lectures/shorts--war-stories--zune-leap-year-freeze--day-366/video.mp4?v=36f75189fec1 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-1-basic-concepts--ask-before-you-draw "Design Twitter." Don't draw a single box yet. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-1-basic-concepts--ask-before-you-draw/poster.jpg?v=912d807064f8 W00 · Foundations: "Design Twitter." Don't draw a single box yet. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-1-basic-concepts--ask-before-you-draw/video.mp4?v=912d807064f8 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-1-basic-concepts--one-more-nine 99% uptime is 3.65 days down a year https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-1-basic-concepts--one-more-nine/poster.jpg?v=cc6ed1a19328 W00 · Foundations: 99% uptime is 3.65 days down a year https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-1-basic-concepts--one-more-nine/video.mp4?v=cc6ed1a19328 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-2-infrastructure-building-blocks--deep-health-check The health check that pulled every server at once https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-2-infrastructure-building-blocks--deep-health-check/poster.jpg?v=4e3334439a0c W00 · Foundations: The health check that pulled every server at once https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-2-infrastructure-building-blocks--deep-health-check/video.mp4?v=4e3334439a0c 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-2-infrastructure-building-blocks--hash-in-the-filename You cached app.js for a year. Then you shipped a bug fix. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-2-infrastructure-building-blocks--hash-in-the-filename/poster.jpg?v=d69b03968450 W00 · Foundations: You cached app.js for a year. Then you shipped a bug fix. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-2-infrastructure-building-blocks--hash-in-the-filename/video.mp4?v=d69b03968450 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-3-back-of-the-envelope-estimation--a-day-is-100k-seconds A day has 86,400 seconds. Pretend it has 100,000. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-3-back-of-the-envelope-estimation--a-day-is-100k-seconds/poster.jpg?v=43cab700f09c W00 · Foundations: A day has 86,400 seconds. Pretend it has 100,000. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-3-back-of-the-envelope-estimation--a-day-is-100k-seconds/video.mp4?v=43cab700f09c 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-3-back-of-the-envelope-estimation--tiny-tweets-huge-media A tweet is 300 bytes. Why does storage hit petabytes? https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-3-back-of-the-envelope-estimation--tiny-tweets-huge-media/poster.jpg?v=4c60699fc1da W00 · Foundations: A tweet is 300 bytes. Why does storage hit petabytes? https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-3-back-of-the-envelope-estimation--tiny-tweets-huge-media/video.mp4?v=4c60699fc1da 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-4-networking--one-lost-packet One lost packet froze all 30 of your HTTP/2 requests https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-4-networking--one-lost-packet/poster.jpg?v=026780c5f4d1 W00 · Foundations: One lost packet froze all 30 of your HTTP/2 requests https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-4-networking--one-lost-packet/video.mp4?v=026780c5f4d1 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-4-networking--out-of-ports "Cannot assign requested address": your server ran out of ports https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-4-networking--out-of-ports/poster.jpg?v=5efbc03f842f W00 · Foundations: "Cannot assign requested address": your server ran out of ports https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-4-networking--out-of-ports/video.mp4?v=5efbc03f842f 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-4-networking--speed-of-light Your API answers in 1 ms. London still waits 55. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-4-networking--speed-of-light/poster.jpg?v=f783598a11e5 W00 · Foundations: Your API answers in 1 ms. London still waits 55. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-4-networking--speed-of-light/video.mp4?v=f783598a11e5 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-5-operating-systems--cpu-bends-memory-breaks Over its CPU limit, your pod slows down. Over memory, it dies. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-5-operating-systems--cpu-bends-memory-breaks/poster.jpg?v=e0ebb853f7a1 W00 · Foundations: Over its CPU limit, your pod slows down. Over memory, it dies. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-5-operating-systems--cpu-bends-memory-breaks/video.mp4?v=e0ebb853f7a1 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-5-operating-systems--one-thread-many-sockets Redis serves thousands of connections from one thread. How? https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-5-operating-systems--one-thread-many-sockets/poster.jpg?v=d32fdff2c287 W00 · Foundations: Redis serves thousands of connections from one thread. How? https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-5-operating-systems--one-thread-many-sockets/video.mp4?v=d32fdff2c287 103 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-5-operating-systems--success-isnt-on-disk write() said success. The power went out. The data is gone. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-5-operating-systems--success-isnt-on-disk/poster.jpg?v=718f003c0894 W00 · Foundations: write() said success. The power went out. The data is gone. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-5-operating-systems--success-isnt-on-disk/video.mp4?v=718f003c0894 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--balance-without-history Your table says the balance is 1,000. Ask it how. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--balance-without-history/poster.jpg?v=83dc32e2fbb3 W00 · Foundations: Your table says the balance is 1,000. Ask it how. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--balance-without-history/video.mp4?v=83dc32e2fbb3 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--cap-isnt-pick-two CAP isn't "pick two of three" https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--cap-isnt-pick-two/poster.jpg?v=ac9452bc118c W00 · Foundations: CAP isn't "pick two of three" https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--cap-isnt-pick-two/video.mp4?v=ac9452bc118c 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--quorum-overlap Three copies, one missed your write. Your read still sees it. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--quorum-overlap/poster.jpg?v=a1ad2d26c6bf W00 · Foundations: Three copies, one missed your write. Your read still sees it. https://media.himanshukukreja.in/lectures/shorts--week-00-foundations--foundations-part-6-terminology-and-theory--quorum-overlap/video.mp4?v=a1ad2d26c6bf 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--capstone-interview-week-1-url-shortner-at-scale--two-promises The primary database dies. Every short link still works. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--capstone-interview-week-1-url-shortner-at-scale--two-promises/poster.jpg?v=17a97461c3ac W01 · Data at scale: The primary database dies. Every short link still works. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--capstone-interview-week-1-url-shortner-at-scale--two-promises/video.mp4?v=17a97461c3ac 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-01-partitioning-deep-dive--its-december 12 partitions. It's December. 11 of them sit idle. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-01-partitioning-deep-dive--its-december/poster.jpg?v=d8c696e46acb W01 · Data at scale: 12 partitions. It's December. 11 of them sit idle. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-01-partitioning-deep-dive--its-december/video.mp4?v=d8c696e46acb 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-01-partitioning-deep-dive--perfect-spread-useless-key A perfect load spread, and a useless partition key https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-01-partitioning-deep-dive--perfect-spread-useless-key/poster.jpg?v=1ab6a994e0a5 W01 · Data at scale: A perfect load spread, and a useless partition key https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-01-partitioning-deep-dive--perfect-spread-useless-key/video.mp4?v=1ab6a994e0a5 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-02-replication-tradeoffs--404-for-a-real-link A 404 for a short link that exists https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-02-replication-tradeoffs--404-for-a-real-link/poster.jpg?v=a713a0027f7e W01 · Data at scale: A 404 for a short link that exists https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-02-replication-tradeoffs--404-for-a-real-link/video.mp4?v=a713a0027f7e 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-02-replication-tradeoffs--data-goes-backwards You refreshed, and your data went back in time https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-02-replication-tradeoffs--data-goes-backwards/poster.jpg?v=5a49c6e4997f W01 · Data at scale: You refreshed, and your data went back in time https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-02-replication-tradeoffs--data-goes-backwards/video.mp4?v=5a49c6e4997f 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--boundary-burst Limit: 10 a minute. 20 got through in 10 seconds. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--boundary-burst/poster.jpg?v=2d336ae9b276 W01 · Data at scale: Limit: 10 a minute. 20 got through in 10 seconds. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--boundary-burst/video.mp4?v=2d336ae9b276 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--fifty-servers-counting Limit: 10 a minute. 50 servers let all 100 through. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--fifty-servers-counting/poster.jpg?v=00bd01515149 W01 · Data at scale: Limit: 10 a minute. 50 servers let all 100 through. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--fifty-servers-counting/video.mp4?v=00bd01515149 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--strict-fallback-five-x Your strict rate-limit fallback lets one user through at five times the limit https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--strict-fallback-five-x/poster.jpg?v=0f485cebec35 W01 · Data at scale: Your strict rate-limit fallback lets one user through at five times the limit https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-03-rate-limiting-at-scale--strict-fallback-five-x/video.mp4?v=0f485cebec35 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-04-hot-keys-and-skew--count-min-sketch Finding hot keys without counting every request https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-04-hot-keys-and-skew--count-min-sketch/poster.jpg?v=f42e0c4ef201 W01 · Data at scale: Finding hot keys without counting every request https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-04-hot-keys-and-skew--count-min-sketch/video.mp4?v=f42e0c4ef201 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-04-hot-keys-and-skew--innocent-neighbours Your link isn't viral. It got 5x slower anyway. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-04-hot-keys-and-skew--innocent-neighbours/poster.jpg?v=224a21126dcc W01 · Data at scale: Your link isn't viral. It got 5x slower anyway. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-04-hot-keys-and-skew--innocent-neighbours/video.mp4?v=224a21126dcc 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-05-session-store-design--log-out-everywhere Stolen laptop. "Log out everywhere." The thief stays in. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-05-session-store-design--log-out-everywhere/poster.jpg?v=db25e53d8568 W01 · Data at scale: Stolen laptop. "Log out everywhere." The thief stays in. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-05-session-store-design--log-out-everywhere/video.mp4?v=db25e53d8568 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-05-session-store-design--planted-session-id The attacker picked your session ID before you logged in https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-05-session-store-design--planted-session-id/poster.jpg?v=6af5d625093c W01 · Data at scale: The attacker picked your session ID before you logged in https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-05-session-store-design--planted-session-id/video.mp4?v=6af5d625093c 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--day-05-session-store-design--price-per-read Same sessions: $2.50 an hour, or over $1,000 https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-05-session-store-design--price-per-read/poster.jpg?v=a39fe593682b W01 · Data at scale: Same sessions: $2.50 an hour, or over $1,000 https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--day-05-session-store-design--price-per-read/video.mp4?v=a39fe593682b 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-01-data-at-scale--week-01-preview--just-use-postgres Just use PostgreSQL? Not at 100 million records. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--week-01-preview--just-use-postgres/poster.jpg?v=506f27fe6588 W01 · Data at scale: Just use PostgreSQL? Not at 100 million records. https://media.himanshukukreja.in/lectures/shorts--week-01-data-at-scale--week-01-preview--just-use-postgres/video.mp4?v=506f27fe6588 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--capstone-interview-week-2-flash-sale-for-megamart--the-leaking-unit A flash sale that quietly loses a unit with every abandoned cart https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--capstone-interview-week-2-flash-sale-for-megamart--the-leaking-unit/poster.jpg?v=265f964b4283 W02 · Failure-first design: A flash sale that quietly loses a unit with every abandoned cart https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--capstone-interview-week-2-flash-sale-for-megamart--the-leaking-unit/video.mp4?v=265f964b4283 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-01-timeout-hell--adaptive-timeout-trap The timeout that tuned itself, and hid a bug for 3 hours https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-01-timeout-hell--adaptive-timeout-trap/poster.jpg?v=aa94c0122107 W02 · Failure-first design: The timeout that tuned itself, and hid a bug for 3 hours https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-01-timeout-hell--adaptive-timeout-trap/video.mp4?v=aa94c0122107 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-01-timeout-hell--deadline-propagation A 5-second request that runs for 8, for a user who already left https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-01-timeout-hell--deadline-propagation/poster.jpg?v=f96d76fde080 W02 · Failure-first design: A 5-second request that runs for 8, for a user who already left https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-01-timeout-hell--deadline-propagation/video.mp4?v=f96d76fde080 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-01-timeout-hell--slow-is-worse-than-down A slow service is worse than a dead one https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-01-timeout-hell--slow-is-worse-than-down/poster.jpg?v=627d09412e97 W02 · Failure-first design: A slow service is worse than a dead one https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-01-timeout-hell--slow-is-worse-than-down/video.mp4?v=627d09412e97 103 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-02-idempotency-in-practice--half-done Charged the customer, failed to pay the merchant: done or failed? https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-02-idempotency-in-practice--half-done/poster.jpg?v=346b4e4ae937 W02 · Failure-first design: Charged the customer, failed to pay the merchant: done or failed? https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-02-idempotency-in-practice--half-done/video.mp4?v=346b4e4ae937 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-02-idempotency-in-practice--key-forgot-too-soon Your idempotency key expired before the payment finished https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-02-idempotency-in-practice--key-forgot-too-soon/poster.jpg?v=7f737f181b9c W02 · Failure-first design: Your idempotency key expired before the payment finished https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-02-idempotency-in-practice--key-forgot-too-soon/video.mp4?v=7f737f181b9c 94 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-03-circuit-breakers--black-friday-trip Your circuit breaker cut off every payment on Black Friday https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-03-circuit-breakers--black-friday-trip/poster.jpg?v=a810a630cc51 W02 · Failure-first design: Your circuit breaker cut off every payment on Black Friday https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-03-circuit-breakers--black-friday-trip/video.mp4?v=a810a630cc51 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-03-circuit-breakers--breaker-hid-the-outage The circuit breaker worked. The outage went unnoticed for 75 minutes. https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-03-circuit-breakers--breaker-hid-the-outage/poster.jpg?v=b3b5b6bf8ab8 W02 · Failure-first design: The circuit breaker worked. The outage went unnoticed for 75 minutes. https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-03-circuit-breakers--breaker-hid-the-outage/video.mp4?v=b3b5b6bf8ab8 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-03-circuit-breakers--recovery-flood The circuit breaker closed. Then it knocked the service down again. https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-03-circuit-breakers--recovery-flood/poster.jpg?v=3ba430333b90 W02 · Failure-first design: The circuit breaker closed. Then it knocked the service down again. https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-03-circuit-breakers--recovery-flood/video.mp4?v=3ba430333b90 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-04-webhook-delivery--aimed-at-your-network A customer pointed your webhooks at your own private network https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-04-webhook-delivery--aimed-at-your-network/poster.jpg?v=98ba87e9c62b W02 · Failure-first design: A customer pointed your webhooks at your own private network https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-04-webhook-delivery--aimed-at-your-network/video.mp4?v=98ba87e9c62b 65 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-04-webhook-delivery--back-at-4-still-waiting The endpoint was back at 4 PM. Webhooks kept arriving until 6. https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-04-webhook-delivery--back-at-4-still-waiting/poster.jpg?v=49d043389d2e W02 · Failure-first design: The endpoint was back at 4 PM. Webhooks kept arriving until 6. https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-04-webhook-delivery--back-at-4-still-waiting/video.mp4?v=49d043389d2e 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-04-webhook-delivery--six-month-replay A six-month-old refund webhook, replayed, with a valid signature https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-04-webhook-delivery--six-month-replay/poster.jpg?v=ca1959f182ea W02 · Failure-first design: A six-month-old refund webhook, replayed, with a valid signature https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-04-webhook-delivery--six-month-replay/video.mp4?v=ca1959f182ea 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--day-05-distributed-cron--three-locks-three-bugs Three servers, one 10 AM job, and three locks that each break https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-05-distributed-cron--three-locks-three-bugs/poster.jpg?v=59a195a4619b W02 · Failure-first design: Three servers, one 10 AM job, and three locks that each break https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--day-05-distributed-cron--three-locks-three-bugs/video.mp4?v=59a195a4619b 102 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-02-failure-first-design--week-02-preview--retry-storm Your retries just quadrupled the load on a failing service https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--week-02-preview--retry-storm/poster.jpg?v=7c175f9c2e9b W02 · Failure-first design: Your retries just quadrupled the load on a failing service https://media.himanshukukreja.in/lectures/shorts--week-02-failure-first-design--week-02-preview--retry-storm/video.mp4?v=7c175f9c2e9b 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--capstone-interview-week-3-event-driven-order-system--charged-no-food "I was charged and never got my food." One query answers it. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--capstone-interview-week-3-event-driven-order-system--charged-no-food/poster.jpg?v=c7167d0285cb W03 · Messaging and async: "I was charged and never got my food." One query answers it. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--capstone-interview-week-3-event-driven-order-system--charged-no-food/video.mp4?v=c7167d0285cb 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-01-queue-vs-stream--idle-consumers You added two consumers. They sit there doing nothing. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-01-queue-vs-stream--idle-consumers/poster.jpg?v=2faddf0bd736 W03 · Messaging and async: You added two consumers. They sit there doing nothing. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-01-queue-vs-stream--idle-consumers/video.mp4?v=2faddf0bd736 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-01-queue-vs-stream--work-or-history "Just use Kafka." Ask one question first. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-01-queue-vs-stream--work-or-history/poster.jpg?v=83d7b6abf537 W03 · Messaging and async: "Just use Kafka." Ask one question first. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-01-queue-vs-stream--work-or-history/video.mp4?v=83d7b6abf537 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-02-transactional-outbox--kafka-down-two-hours Kafka was down for 2 hours. Not one order event was lost. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-02-transactional-outbox--kafka-down-two-hours/poster.jpg?v=4afea19a05d9 W03 · Messaging and async: Kafka was down for 2 hours. Not one order event was lost. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-02-transactional-outbox--kafka-down-two-hours/video.mp4?v=4afea19a05d9 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-02-transactional-outbox--two-innocent-lines Save the order, then publish the event. 23 orders vanished. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-02-transactional-outbox--two-innocent-lines/poster.jpg?v=1d33b0860791 W03 · Messaging and async: Save the order, then publish the event. 23 orders vanished. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-02-transactional-outbox--two-innocent-lines/video.mp4?v=1d33b0860791 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--delay-not-reject LinkedIn's Kafka doesn't reject a runaway producer. It just answers slowly. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--delay-not-reject/poster.jpg?v=0fcb74bf2ea4 W03 · Messaging and async: LinkedIn's Kafka doesn't reject a runaway producer. It just answers slowly. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--delay-not-reject/video.mp4?v=0fcb74bf2ea4 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--no-brake Built for 5,000 a second. Hit with 200,000. Down in 10 minutes. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--no-brake/poster.jpg?v=b25c2e2f31ab W03 · Messaging and async: Built for 5,000 a second. Hit with 200,000. Down in 10 minutes. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--no-brake/video.mp4?v=b25c2e2f31ab 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--throw-it-away Under overload, the right move is to throw data away. Some of it. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--throw-it-away/poster.jpg?v=d31d540f8430 W03 · Messaging and async: Under overload, the right move is to throw data away. Some of it. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-03-backpressure-and-flow-control--throw-it-away/video.mp4?v=d31d540f8430 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--fixed-then-failed-again You fixed the bug and replayed the dead letter. It failed again. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--fixed-then-failed-again/poster.jpg?v=df8813f3bbe6 W03 · Messaging and async: You fixed the bug and replayed the dead letter. It failed again. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--fixed-then-failed-again/video.mp4?v=df8813f3bbe6 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--one-bad-field One malformed field froze checkout for 4 hours https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--one-bad-field/poster.jpg?v=ce3f826656fc W03 · Messaging and async: One malformed field froze checkout for 4 hours https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--one-bad-field/video.mp4?v=ce3f826656fc 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--retry-one-of-three "Retry 1 of 3", logged forever https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--retry-one-of-three/poster.jpg?v=c8cc24ab0d26 W03 · Messaging and async: "Retry 1 of 3", logged forever https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-04-dead-letters-and-poison-pills--retry-one-of-three/video.mp4?v=c8cc24ab0d26 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-05-audit-log-system--five-seconds-fast One server's clock ran 5 seconds fast. The audit log told the wrong story. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-05-audit-log-system--five-seconds-fast/poster.jpg?v=00840c553cf2 W03 · Messaging and async: One server's clock ran 5 seconds fast. The audit log told the wrong story. https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-05-audit-log-system--five-seconds-fast/video.mp4?v=00840c553cf2 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--day-05-audit-log-system--hash-chain How an audit log proves nobody edited it https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-05-audit-log-system--hash-chain/poster.jpg?v=94e97d0658cd W03 · Messaging and async: How an audit log proves nobody edited it https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--day-05-audit-log-system--hash-chain/video.mp4?v=94e97d0658cd 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-03-messaging-and-async-processing--week-03-preview--chains-multiply Five services at 99.9% give you 99.5% https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--week-03-preview--chains-multiply/poster.jpg?v=ac58e1f45273 W03 · Messaging and async: Five services at 99.9% give you 99.5% https://media.himanshukukreja.in/lectures/shorts--week-03-messaging-and-async-processing--week-03-preview--chains-multiply/video.mp4?v=ac58e1f45273 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--capstone-interview-week-4-ecommerce-product-catalog--one-point-of-hit-ratio Your hit ratio slips one point. Your database load doubles. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--capstone-interview-week-4-ecommerce-product-catalog--one-point-of-hit-ratio/poster.jpg?v=2ec7ef203009 W04 · Caching: Your hit ratio slips one point. Your database load doubles. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--capstone-interview-week-4-ecommerce-product-catalog--one-point-of-hit-ratio/video.mp4?v=2ec7ef203009 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--capstone-interview-week-4-ecommerce-product-catalog--redis-dies-mid-sale Redis dies mid flash sale. Don't fall back to the database. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--capstone-interview-week-4-ecommerce-product-catalog--redis-dies-mid-sale/poster.jpg?v=7d0eb7ec29ea W04 · Caching: Redis dies mid flash sale. Don't fall back to the database. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--capstone-interview-week-4-ecommerce-product-catalog--redis-dies-mid-sale/video.mp4?v=7d0eb7ec29ea 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-01-caching-patterns--cache-more-hit-less You cached more. Your hit ratio went down. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-01-caching-patterns--cache-more-hit-less/poster.jpg?v=3737cde88590 W04 · Caching: You cached more. Your hit ratio went down. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-01-caching-patterns--cache-more-hit-less/video.mp4?v=3737cde88590 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-01-caching-patterns--cold-after-restart You restarted one service. The database took 100 times the load. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-01-caching-patterns--cold-after-restart/poster.jpg?v=dcf6fff3435e W04 · Caching: You restarted one service. The database took 100 times the load. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-01-caching-patterns--cold-after-restart/video.mp4?v=dcf6fff3435e 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-01-caching-patterns--dead-cache-just-slower Redis died. Should your whole site die with it? https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-01-caching-patterns--dead-cache-just-slower/poster.jpg?v=15845b6f9660 W04 · Caching: Redis died. Should your whole site die with it? https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-01-caching-patterns--dead-cache-just-slower/video.mp4?v=15845b6f9660 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-02-cache-invalidation--delete-dont-update Two price updates. The database is right. The cache is wrong. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-02-cache-invalidation--delete-dont-update/poster.jpg?v=d3eac868ee24 W04 · Caching: Two price updates. The database is right. The cache is wrong. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-02-cache-invalidation--delete-dont-update/video.mp4?v=d3eac868ee24 87 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-02-cache-invalidation--deleted-too-early You deleted the cache key. The old price came back anyway. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-02-cache-invalidation--deleted-too-early/poster.jpg?v=02e7a35007da W04 · Caching: You deleted the cache key. The old price came back anyway. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-02-cache-invalidation--deleted-too-early/video.mp4?v=02e7a35007da 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-02-cache-invalidation--never-stale-forever The page said $99. The card was charged $79. For an hour. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-02-cache-invalidation--never-stale-forever/poster.jpg?v=e0c80007b33f W04 · Caching: The page said $99. The card was charged $79. For an hour. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-02-cache-invalidation--never-stale-forever/video.mp4?v=e0c80007b33f 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-03-thundering-herd--keys-expire-together Your own deploy built a thundering herd, five minutes later https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-03-thundering-herd--keys-expire-together/poster.jpg?v=e30b95b76d58 W04 · Caching: Your own deploy built a thundering herd, five minutes later https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-03-thundering-herd--keys-expire-together/video.mp4?v=e30b95b76d58 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-03-thundering-herd--one-miss-one-query One expired key took down Black Friday https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-03-thundering-herd--one-miss-one-query/poster.jpg?v=6b94d345118d W04 · Caching: One expired key took down Black Friday https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-03-thundering-herd--one-miss-one-query/video.mp4?v=6b94d345118d 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-03-thundering-herd--stale-window-cliff Serving stale data saved you. Then, at second 300, it stopped. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-03-thundering-herd--stale-window-cliff/poster.jpg?v=a8bb35495f29 W04 · Caching: Serving stale data saved you. Then, at second 300, it stopped. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-03-thundering-herd--stale-window-cliff/video.mp4?v=a8bb35495f29 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-04-feed-caching--why-linkedin-pulls Why LinkedIn builds your feed when you open it https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-04-feed-caching--why-linkedin-pulls/poster.jpg?v=ee4cec8c29d7 W04 · Caching: Why LinkedIn builds your feed when you open it https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-04-feed-caching--why-linkedin-pulls/video.mp4?v=ee4cec8c29d7 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-05-multi-tier-caching--invalidate-inside-out You purged the CDN. Seconds later it served the old price again. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-05-multi-tier-caching--invalidate-inside-out/poster.jpg?v=b4fb64f38bbd W04 · Caching: You purged the CDN. Seconds later it served the old price again. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-05-multi-tier-caching--invalidate-inside-out/video.mp4?v=b4fb64f38bbd 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--day-05-multi-tier-caching--vary-on-language Your French users are reading English. Your CDN did it. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-05-multi-tier-caching--vary-on-language/poster.jpg?v=3e5d6c44e798 W04 · Caching: Your French users are reading English. Your CDN did it. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--day-05-multi-tier-caching--vary-on-language/video.mp4?v=3e5d6c44e798 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-04-caching--week-04-preview--cache-lies Just add Redis. Then the sale ends and your cache never hears. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--week-04-preview--cache-lies/poster.jpg?v=9c88803e6c75 W04 · Caching: Just add Redis. Then the sale ends and your cache never hears. https://media.himanshukukreja.in/lectures/shorts--week-04-caching--week-04-preview--cache-lies/video.mp4?v=9c88803e6c75 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--capstone-interview-week-5-multiplayer-game-matchmaking-system--a-tiny-queue 2 million players online. The matchmaking queue is 2.4 MB. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--capstone-interview-week-5-multiplayer-game-matchmaking-system--a-tiny-queue/poster.jpg?v=4663b05623ea W05 · Consistency and coordination: 2 million players online. The matchmaking queue is 2.4 MB. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--capstone-interview-week-5-multiplayer-game-matchmaking-system--a-tiny-queue/video.mp4?v=4663b05623ea 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-01-consistency-models--fresh-where-you-look Facebook lets your friends' data be a second old. Never yours. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-01-consistency-models--fresh-where-you-look/poster.jpg?v=fce5cfc0810d W05 · Consistency and coordination: Facebook lets your friends' data be a second old. Never yours. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-01-consistency-models--fresh-where-you-look/video.mp4?v=fce5cfc0810d 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-01-consistency-models--spanner-waits Google Spanner is consistent across continents. The trick: it waits. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-01-consistency-models--spanner-waits/poster.jpg?v=81da60180563 W05 · Consistency and coordination: Google Spanner is consistent across continents. The trick: it waits. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-01-consistency-models--spanner-waits/video.mp4?v=81da60180563 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--easiest-to-cancel-first Flight, hotel, car: which do you book first? https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--easiest-to-cancel-first/poster.jpg?v=262a82d66a3e W05 · Consistency and coordination: Flight, hotel, car: which do you book first? https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--easiest-to-cancel-first/video.mp4?v=262a82d66a3e 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--the-silent-coordinator Every service said ready. Then the coordinator died. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--the-silent-coordinator/poster.jpg?v=513a187eb70b W05 · Consistency and coordination: Every service said ready. Then the coordinator died. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--the-silent-coordinator/video.mp4?v=513a187eb70b 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--you-cant-unship The parcel has shipped. Then the confirmation email fails. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--you-cant-unship/poster.jpg?v=3f1163a837e2 W05 · Consistency and coordination: The parcel has shipped. Then the confirmation email fails. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-02-saga-pattern--you-cant-unship/video.mp4?v=3f1163a837e2 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-03-saga-orchestration--history-never-shrinks A workflow that loops forever. Temporal will end it. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-03-saga-orchestration--history-never-shrinks/poster.jpg?v=93258dd03f4c W05 · Consistency and coordination: A workflow that loops forever. Temporal will end it. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-03-saga-orchestration--history-never-shrinks/video.mp4?v=93258dd03f4c 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-03-saga-orchestration--the-promo-clock One read of the clock breaks a workflow, hours later https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-03-saga-orchestration--the-promo-clock/poster.jpg?v=0e6255a37a68 W05 · Consistency and coordination: One read of the clock breaks a workflow, hours later https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-03-saga-orchestration--the-promo-clock/video.mp4?v=0e6255a37a68 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-04-conflict-resolution--add-wins Removed on your phone, re-added on your laptop. Is it in the cart? https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-04-conflict-resolution--add-wins/poster.jpg?v=9b76dcfa0bf6 W05 · Consistency and coordination: Removed on your phone, re-added on your laptop. Is it in the cart? https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-04-conflict-resolution--add-wins/video.mp4?v=9b76dcfa0bf6 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-04-conflict-resolution--two-likes-one-count Two people like a post at once. The count goes up by one. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-04-conflict-resolution--two-likes-one-count/poster.jpg?v=e6f961c1019f W05 · Consistency and coordination: Two people like a post at once. The count goes up by one. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-04-conflict-resolution--two-likes-one-count/video.mp4?v=e6f961c1019f 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-05-leader-election--a-leader-steps-down A network split leaves the leader with one friend. It should quit. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-05-leader-election--a-leader-steps-down/poster.jpg?v=a01a800fdbed W05 · Consistency and coordination: A network split leaves the leader with one friend. It should quit. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-05-leader-election--a-leader-steps-down/video.mp4?v=a01a800fdbed 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--day-05-leader-election--one-sentinel-isnt-enough One Sentinel says the Redis master is dead. Nothing happens. Good. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-05-leader-election--one-sentinel-isnt-enough/poster.jpg?v=75a1d4ab026d W05 · Consistency and coordination: One Sentinel says the Redis master is dead. Nothing happens. Good. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--day-05-leader-election--one-sentinel-isnt-enough/video.mp4?v=75a1d4ab026d 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-05-consistency-and-coordination--week-05-preview--one-left-two-sold One item left. Two buyers. You sold both. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--week-05-preview--one-left-two-sold/poster.jpg?v=f3fde006b3a0 W05 · Consistency and coordination: One item left. Two buyers. You sold both. https://media.himanshukukreja.in/lectures/shorts--week-05-consistency-and-coordination--week-05-preview--one-left-two-sold/video.mp4?v=f3fde006b3a0 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system--locked-out-by-retries Your rate limiter counted the rejections. Now a retrying client never gets back in. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system--locked-out-by-retries/poster.jpg?v=3f232f63400d W06 · Notification platform: Your rate limiter counted the rejections. Now a retrying client never gets back in. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system--locked-out-by-retries/video.mp4?v=3f232f63400d 90 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system--stored-the-timeout Your idempotency store saved a timeout. Now every retry fails for 24 hours. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system--stored-the-timeout/poster.jpg?v=9fdc798abe44 W06 · Notification platform: Your idempotency store saved a timeout. Now every retry fails for 24 hours. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--capstone-interview-week-6-food-delivery-system--stored-the-timeout/video.mp4?v=9fdc798abe44 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-01-notification-platform-design--sms-is-the-bill SMS is 5% of the notifications and almost all of the bill https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-01-notification-platform-design--sms-is-the-bill/poster.jpg?v=b98b2b117063 W06 · Notification platform: SMS is 5% of the notifications and almost all of the bill https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-01-notification-platform-design--sms-is-the-bill/video.mp4?v=b98b2b117063 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-02-core-notification-flow--skipped-not-retried Routing failed, so you didn't commit. The message was skipped anyway. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-02-core-notification-flow--skipped-not-retried/poster.jpg?v=a8d1a751dc7a W06 · Notification platform: Routing failed, so you didn't commit. The message was skipped anyway. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-02-core-notification-flow--skipped-not-retried/video.mp4?v=a8d1a751dc7a 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-02-core-notification-flow--the-overnight-bug Quiet hours, 10 PM to 8 AM. At 11:30 PM, the marketing push buzzes. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-02-core-notification-flow--the-overnight-bug/poster.jpg?v=b4fce030a739 W06 · Notification platform: Quiet hours, 10 PM to 8 AM. At 11:30 PM, the marketing push buzzes. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-02-core-notification-flow--the-overnight-bug/video.mp4?v=b4fce030a739 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-03-advanced-features--escalate-on-silence Delivered but never opened: when a push escalates to a phone call https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-03-advanced-features--escalate-on-silence/poster.jpg?v=fbefea7b5a3f W06 · Notification platform: Delivered but never opened: when a push escalates to a phone call https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-03-advanced-features--escalate-on-silence/video.mp4?v=fbefea7b5a3f 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-03-advanced-features--the-fourth-like Three likes got batched. The fourth was never sent. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-03-advanced-features--the-fourth-like/poster.jpg?v=4abef9bf32f9 W06 · Notification platform: Three likes got batched. The fourth was never sent. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-03-advanced-features--the-fourth-like/video.mp4?v=4abef9bf32f9 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--check-again-at-send You unsubscribed. The campaign was already queued. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--check-again-at-send/poster.jpg?v=0a86193789a3 W06 · Notification platform: You unsubscribed. The campaign was already queued. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--check-again-at-send/video.mp4?v=0a86193789a3 91 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--key-by-recipient A celebrity posts. One Kafka consumer does a million sends alone. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--key-by-recipient/poster.jpg?v=16e25e251d43 W06 · Notification platform: A celebrity posts. One Kafka consumer does a million sends alone. https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--key-by-recipient/video.mp4?v=16e25e251d43 77 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--the-hour-that-never-happens A reminder for 2:30 AM, on a night when 2:30 AM never happens https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--the-hour-that-never-happens/poster.jpg?v=2613274217cc W06 · Notification platform: A reminder for 2:30 AM, on a night when 2:30 AM never happens https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-04-scale-reliability-edge-cases--the-hour-that-never-happens/video.mp4?v=2613274217cc 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--day-05-operations-monitoring-interview--page-on-symptoms A circuit breaker opened at 3 AM. Should anyone wake up? https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-05-operations-monitoring-interview--page-on-symptoms/poster.jpg?v=430afb4bd28f W06 · Notification platform: A circuit breaker opened at 3 AM. Should anyone wake up? https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--day-05-operations-monitoring-interview--page-on-symptoms/video.mp4?v=430afb4bd28f 72 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-06-designing-notification-platform--week-06-preview--dead-device-token New phone, old push token: why retrying never works https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--week-06-preview--dead-device-token/poster.jpg?v=8bab64c8c954 W06 · Notification platform: New phone, old push token: why retrying never works https://media.himanshukukreja.in/lectures/shorts--week-06-designing-notification-platform--week-06-preview--dead-device-token/video.mp4?v=8bab64c8c954 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--capstone-interview-week-7-legal-document-search--one-attempt-pages Most alerts need a threshold. This one fires at one. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--capstone-interview-week-7-legal-document-search--one-attempt-pages/poster.jpg?v=cf8c0ffa860a W07 · Search system: Most alerts need a threshold. This one fires at one. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--capstone-interview-week-7-legal-document-search--one-attempt-pages/video.mp4?v=cf8c0ffa860a 93 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--capstone-interview-week-7-legal-document-search--still-good-law 15,234 cases cite it. Is it still good law? https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--capstone-interview-week-7-legal-document-search--still-good-law/poster.jpg?v=615f43e4cd3f W07 · Search system: 15,234 cases cite it. Is it still good law? https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--capstone-interview-week-7-legal-document-search--still-good-law/video.mp4?v=615f43e4cd3f 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-01-search-fundamentals--same-analyzer-both-sides A store full of running shoes. Search running shoes: no results. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-01-search-fundamentals--same-analyzer-both-sides/poster.jpg?v=973cec6e13c0 W07 · Search system: A store full of running shoes. Search running shoes: no results. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-01-search-fundamentals--same-analyzer-both-sides/video.mp4?v=973cec6e13c0 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-01-search-fundamentals--search-red-get-bored Search for red. Your store shows Bored Games. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-01-search-fundamentals--search-red-get-bored/poster.jpg?v=37985dbe293d W07 · Search system: Search for red. Your store shows Bored Games. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-01-search-fundamentals--search-red-get-bored/video.mp4?v=37985dbe293d 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-02-indexing-pipeline--bulk-import-lane A million new products, invisible to search for 3 hours https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-02-indexing-pipeline--bulk-import-lane/poster.jpg?v=7c1fd9a7bd20 W07 · Search system: A million new products, invisible to search for 3 hours https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-02-indexing-pipeline--bulk-import-lane/video.mp4?v=7c1fd9a7bd20 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-02-indexing-pipeline--reindex-behind-an-alias Rebuild the whole search index, and nobody notices https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-02-indexing-pipeline--reindex-behind-an-alias/poster.jpg?v=e27abc2c1543 W07 · Search system: Rebuild the whole search index, and nobody notices https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-02-indexing-pipeline--reindex-behind-an-alias/video.mp4?v=e27abc2c1543 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-02-indexing-pipeline--search-said-120 Search said $120. Checkout said $150. "This is a scam." https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-02-indexing-pipeline--search-said-120/poster.jpg?v=504e5c6d53eb W07 · Search system: Search said $120. Checkout said $150. "This is a scam." https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-02-indexing-pipeline--search-said-120/video.mp4?v=504e5c6d53eb 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-03-query-processing-relevance--never-no-results The product exists. Search says no results. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-03-query-processing-relevance--never-no-results/poster.jpg?v=b6e70bafcce3 W07 · Search system: The product exists. Search says no results. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-03-query-processing-relevance--never-no-results/video.mp4?v=b6e70bafcce3 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-03-query-processing-relevance--short-beats-long Same two words. A 45-word review beats a 150-word guide, nearly 3 to 1. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-03-query-processing-relevance--short-beats-long/poster.jpg?v=6c61869544bf W07 · Search system: Same two words. A 45-word review beats a 150-word guide, nearly 3 to 1. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-03-query-processing-relevance--short-beats-long/video.mp4?v=6c61869544bf 83 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-03-query-processing-relevance--typed-vs-selected Your search works. It's slower and ranks worse. Three filters in must. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-03-query-processing-relevance--typed-vs-selected/poster.jpg?v=a8449f4e511d W07 · Search system: Your search works. It's slower and ranks worse. Three filters in must. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-03-query-processing-relevance--typed-vs-selected/video.mp4?v=a8449f4e511d 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-04-advanced-search-features--prefixes-at-index-time Autocomplete breaks the same-analyzer rule, on purpose https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-04-advanced-search-features--prefixes-at-index-time/poster.jpg?v=8d880cd3161d W07 · Search system: Autocomplete breaks the same-analyzer rule, on purpose https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-04-advanced-search-features--prefixes-at-index-time/video.mp4?v=8d880cd3161d 88 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-04-advanced-search-features--tick-nike-lose-adidas Tick Nike, and you can't add Adidas. Facets done wrong. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-04-advanced-search-features--tick-nike-lose-adidas/poster.jpg?v=d71437f5d0eb W07 · Search system: Tick Nike, and you can't add Adidas. Facets done wrong. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-04-advanced-search-features--tick-nike-lose-adidas/video.mp4?v=d71437f5d0eb 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--day-05-search-operations-scale--the-fix-was-yesterday 3 AM, Black Friday, search is melting. The fix was 24 hours ago. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-05-search-operations-scale--the-fix-was-yesterday/poster.jpg?v=14fad0356e53 W07 · Search system: 3 AM, Black Friday, search is melting. The fix was 24 hours ago. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--day-05-search-operations-scale--the-fix-was-yesterday/video.mp4?v=14fad0356e53 89 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-07-designing-search-system--week-07-preview--thirty-second-search Your search took 30 seconds. A search engine takes 50 ms. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--week-07-preview--thirty-second-search/poster.jpg?v=479846b51d14 W07 · Search system: Your search took 30 seconds. A search engine takes 50 ms. https://media.himanshukukreja.in/lectures/shorts--week-07-designing-search-system--week-07-preview--thirty-second-search/video.mp4?v=479846b51d14 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics--unusually-popular Rank trending by counting plays, and the longest movie always wins https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics--unusually-popular/poster.jpg?v=7933b4e60c06 W08 · Analytics pipeline: Rank trending by counting plays, and the longest movie always wins https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics--unusually-popular/video.mp4?v=7933b4e60c06 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics--viewer-days Add up 30 days of unique viewers, and you get the wrong number https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics--viewer-days/poster.jpg?v=1c0e8667c60e W08 · Analytics pipeline: Add up 30 days of unique viewers, and you get the wrong number https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--capstone-interview-week-8-streaming-analytics--viewer-days/video.mp4?v=1c0e8667c60e 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-01-event-ingestion--one-bad-event 500 events in one upload. 3 are broken. Reject all 500? https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-01-event-ingestion--one-bad-event/poster.jpg?v=750e48d7b672 W08 · Analytics pipeline: 500 events in one upload. 3 are broken. Reject all 500? https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-01-event-ingestion--one-bad-event/video.mp4?v=750e48d7b672 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-01-event-ingestion--shed-page-views Flash sale. Your event queue is 95% full. What do you drop? https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-01-event-ingestion--shed-page-views/poster.jpg?v=206301a2bd22 W08 · Analytics pipeline: Flash sale. Your event queue is 95% full. What do you drop? https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-01-event-ingestion--shed-page-views/video.mp4?v=206301a2bd22 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-02-streaming-vs-batch--incremental-trap Your incremental batch job will never count this late event https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-02-streaming-vs-batch--incremental-trap/poster.jpg?v=048e665b30f3 W08 · Analytics pipeline: Your incremental batch job will never count this late event https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-02-streaming-vs-batch--incremental-trap/video.mp4?v=048e665b30f3 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-02-streaming-vs-batch--same-logic-twice Lambda makes you write every metric twice. Kappa's price is the replay. https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-02-streaming-vs-batch--same-logic-twice/poster.jpg?v=e7e9c6769911 W08 · Analytics pipeline: Lambda makes you write every metric twice. Kappa's price is the replay. https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-02-streaming-vs-batch--same-logic-twice/video.mp4?v=e7e9c6769911 82 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-03-data-modeling--grain-too-coarse Your fact table can't say which products sold. No index can fix it. https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-03-data-modeling--grain-too-coarse/poster.jpg?v=b7f332029176 W08 · Analytics pipeline: Your fact table can't say which products sold. No index can fix it. https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-03-data-modeling--grain-too-coarse/video.mp4?v=b7f332029176 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-03-data-modeling--standard-or-premium John upgraded in June. Which segment gets his Q1 spending? https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-03-data-modeling--standard-or-premium/poster.jpg?v=fdb9beb761b1 W08 · Analytics pipeline: John upgraded in June. Which segment gets his Q1 spending? https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-03-data-modeling--standard-or-premium/video.mp4?v=fdb9beb761b1 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-04-late-data--idle-phone One phone offline for two days froze every window on the dashboard https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-04-late-data--idle-phone/poster.jpg?v=ed35d93a6275 W08 · Analytics pipeline: One phone offline for two days froze every window on the dashboard https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-04-late-data--idle-phone/video.mp4?v=ed35d93a6275 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-04-late-data--measure-dont-guess How long should a dashboard wait for late events? Measure it. https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-04-late-data--measure-dont-guess/poster.jpg?v=7cd520fe47d1 W08 · Analytics pipeline: How long should a dashboard wait for late events? Measure it. https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-04-late-data--measure-dont-guess/video.mp4?v=7cd520fe47d1 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-04-late-data--numbers-changed-overnight The weekend sale made $127,000 more on Monday morning https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-04-late-data--numbers-changed-overnight/poster.jpg?v=08dd92e517c1 W08 · Analytics pipeline: The weekend sale made $127,000 more on Monday morning https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-04-late-data--numbers-changed-overnight/video.mp4?v=08dd92e517c1 81 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--day-05-query-optimization--rollup-ladder A 47-second dashboard, answered from a few thousand rows https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-05-query-optimization--rollup-ladder/poster.jpg?v=684891d76bb6 W08 · Analytics pipeline: A 47-second dashboard, answered from a few thousand rows https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--day-05-query-optimization--rollup-ladder/video.mp4?v=684891d76bb6 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-08-designing-analytics-pipeline--week-08-preview--rows-not-answers 100 million events a day, and not one of them is an answer https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--week-08-preview--rows-not-answers/poster.jpg?v=71504dd74c0e W08 · Analytics pipeline: 100 million events a day, and not one of them is an answer https://media.himanshukukreja.in/lectures/shorts--week-08-designing-analytics-pipeline--week-08-preview--rows-not-answers/video.mp4?v=71504dd74c0e 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--capstone-interview-week-9-multi-tenant-saas--quarter-end-queue One export job, stuck behind another tenant's 50,000 https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--capstone-interview-week-9-multi-tenant-saas--quarter-end-queue/poster.jpg?v=9474b5c66a5e W09 · Multi-tenancy and security: One export job, stuck behind another tenant's 50,000 https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--capstone-interview-week-9-multi-tenant-saas--quarter-end-queue/video.mp4?v=9474b5c66a5e 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--half-migrated A migration failed on tenant schema 4,000 of 10,000 https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--half-migrated/poster.jpg?v=934f736f8cdc W09 · Multi-tenancy and security: A migration failed on tenant schema 4,000 of 10,000 https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--half-migrated/video.mp4?v=934f736f8cdc 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--pool-remembers No query had a bug. Another tenant still got Tenant A's rows. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--pool-remembers/poster.jpg?v=e1b254566137 W09 · Multi-tenancy and security: No query had a bug. Another tenant still got Tenant A's rows. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--pool-remembers/video.mp4?v=e1b254566137 79 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--same-user-123 Two companies, two users called 123, one cache key https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--same-user-123/poster.jpg?v=3d1e352dd0da W09 · Multi-tenancy and security: Two companies, two users called 123, one cache key https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-01-tenant-isolation--same-user-123/video.mp4?v=3d1e352dd0da 69 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-02-noisy-neighbour--governor-limits Salesforce fails your transaction at query 101. On purpose. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-02-noisy-neighbour--governor-limits/poster.jpg?v=471bd8137c27 W09 · Multi-tenancy and security: Salesforce fails your transaction at query 101. On purpose. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-02-noisy-neighbour--governor-limits/video.mp4?v=471bd8137c27 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-02-noisy-neighbour--one-report One customer's export report took down 500 other customers https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-02-noisy-neighbour--one-report/poster.jpg?v=899e41f6dc75 W09 · Multi-tenancy and security: One customer's export report took down 500 other customers https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-02-noisy-neighbour--one-report/video.mp4?v=899e41f6dc75 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-03-data-residency--follows-the-tenant An EU employee uploads a file from the US. Where is it stored? https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-03-data-residency--follows-the-tenant/poster.jpg?v=e01e8e57fd68 W09 · Multi-tenancy and security: An EU employee uploads a file from the US. Where is it stored? https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-03-data-residency--follows-the-tenant/video.mp4?v=e01e8e57fd68 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-03-data-residency--frankfurt-backups Your EU data is in Frankfurt. Your backups aren't. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-03-data-residency--frankfurt-backups/poster.jpg?v=6872137197f1 W09 · Multi-tenancy and security: Your EU data is in Frankfurt. Your backups aren't. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-03-data-residency--frankfurt-backups/video.mp4?v=6872137197f1 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--cache-goes-last Deleting a user from every system? The cache goes last. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--cache-goes-last/poster.jpg?v=7c7340efd838 W09 · Multi-tenancy and security: Deleting a user from every system? The cache goes last. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--cache-goes-last/video.mp4?v=7c7340efd838 78 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--prove-its-gone The user's data is gone. Now prove you deleted it. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--prove-its-gone/poster.jpg?v=b805bd4cd189 W09 · Multi-tenancy and security: The user's data is gone. Now prove you deleted it. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--prove-its-gone/video.mp4?v=b805bd4cd189 84 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--restore-resurrects A deleted user came back to life in a backup restore https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--restore-resurrects/poster.jpg?v=069c69da22cf W09 · Multi-tenancy and security: A deleted user came back to life in a backup restore https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-04-right-to-deletion--restore-resurrects/video.mp4?v=069c69da22cf 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-05-security-architecture--dba-sees-plaintext The database is encrypted. The DBA still reads every SSN. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-05-security-architecture--dba-sees-plaintext/poster.jpg?v=f6400a1899bf W09 · Multi-tenancy and security: The database is encrypted. The DBA still reads every SSN. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-05-security-architecture--dba-sees-plaintext/video.mp4?v=f6400a1899bf 73 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-05-security-architecture--invalid-credentials Why login never says 'no account with that email' https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-05-security-architecture--invalid-credentials/poster.jpg?v=b6b3356d8cca W09 · Multi-tenancy and security: Why login never says 'no account with that email' https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-05-security-architecture--invalid-credentials/video.mp4?v=b6b3356d8cca 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--day-05-security-architecture--rotate-dont-delete A database password was committed. Deleting the line won't help. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-05-security-architecture--rotate-dont-delete/poster.jpg?v=b6ed2a5e9bab W09 · Multi-tenancy and security: A database password was committed. Deleting the line won't help. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--day-05-security-architecture--rotate-dont-delete/video.mp4?v=b6ed2a5e9bab 76 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-09-multi-tanency-security--week-09-preview--the-questionnaire You landed the enterprise deal. Then came the security questionnaire. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--week-09-preview--the-questionnaire/poster.jpg?v=cbebae051a6f W09 · Multi-tenancy and security: You landed the enterprise deal. Then came the security questionnaire. https://media.himanshukukreja.in/lectures/shorts--week-09-multi-tanency-security--week-09-preview--the-questionnaire/video.mp4?v=cbebae051a6f 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--budget-leases $10 left in the budget. 1,000 servers each approved a $20 bid. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--budget-leases/poster.jpg?v=6a1ea24519af W10 · Production readiness: $10 left in the budget. 1,000 servers each approved a $20 bid. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--budget-leases/video.mp4?v=6a1ea24519af 85 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--fraud-in-five-ms Bot or human? An ad platform gets 5 milliseconds to decide. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--fraud-in-five-ms/poster.jpg?v=608224fb3800 W10 · Production readiness: Bot or human? An ad platform gets 5 milliseconds to decide. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--fraud-in-five-ms/video.mp4?v=608224fb3800 95 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--latency-budget 100 milliseconds to sell an ad. Where every one of them goes. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--latency-budget/poster.jpg?v=a06c46a3f071 W10 · Production readiness: 100 milliseconds to sell an ad. Where every one of them goes. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--capstone-interview-week-10-the-grand-finale--latency-budget/video.mp4?v=a06c46a3f071 86 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--blip-no-page Errors hit 5% for 3 minutes. Nobody got paged. Correctly. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--blip-no-page/poster.jpg?v=927048e83a60 W10 · Production readiness: Errors hit 5% for 3 minutes. Nobody got paged. Correctly. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--blip-no-page/video.mp4?v=927048e83a60 80 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--dependency-ceiling You promise 99.9%. Your dependencies allow 99.83%. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--dependency-ceiling/poster.jpg?v=230d1211a9ec W10 · Production readiness: You promise 99.9%. Your dependencies allow 99.83%. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--dependency-ceiling/video.mp4?v=230d1211a9ec 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--error-budget A 99.9% SLO gives you 43.2 minutes a month. Then features stop. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--error-budget/poster.jpg?v=1eed95bd9401 W10 · Production readiness: A 99.9% SLO gives you 43.2 minutes a month. Then features stop. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-01-slis-slos-slas--error-budget/video.mp4?v=1eed95bd9401 67 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-02-observability--slow-not-failing p99 jumped from 200 ms to 2.3 seconds, with zero extra errors https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-02-observability--slow-not-failing/poster.jpg?v=1b68dcf4cf33 W10 · Production readiness: p99 jumped from 200 ms to 2.3 seconds, with zero extra errors https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-02-observability--slow-not-failing/video.mp4?v=1b68dcf4cf33 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-02-observability--twenty-p99s 20 pods each report a p99. What is the fleet's p99? https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-02-observability--twenty-p99s/poster.jpg?v=efa6893fede6 W10 · Production readiness: 20 pods each report a p99. What is the fleet's p99? https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-02-observability--twenty-p99s/video.mp4?v=efa6893fede6 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies--rename-breaks-old-code Renaming one column broke your old servers mid-deploy https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies--rename-breaks-old-code/poster.jpg?v=414532d0e20d W10 · Production readiness: Renaming one column broke your old servers mid-deploy https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies--rename-breaks-old-code/video.mp4?v=414532d0e20d 74 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies--same-user-same-bucket A 10% rollout that flips users between two checkouts on every refresh https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies--same-user-same-bucket/poster.jpg?v=5f942deab431 W10 · Production readiness: A 10% rollout that flips users between two checkouts on every refresh https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-03-deployment-strategies--same-user-same-bucket/video.mp4?v=5f942deab431 68 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-04-capacity-planning--littles-law-spiral 50% more traffic didn't make the API 50% slower. It started a spiral. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-04-capacity-planning--littles-law-spiral/poster.jpg?v=0bca94b34e91 W10 · Production readiness: 50% more traffic didn't make the API 50% slower. It started a spiral. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-04-capacity-planning--littles-law-spiral/video.mp4?v=0bca94b34e91 70 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-04-capacity-planning--ninety-percent-busy At 90% busy, every request waits about 9 times longer https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-04-capacity-planning--ninety-percent-busy/poster.jpg?v=51aff13ae032 W10 · Production readiness: At 90% busy, every request waits about 9 times longer https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-04-capacity-planning--ninety-percent-busy/video.mp4?v=51aff13ae032 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--ic-doesnt-debug The person running the outage shouldn't touch the code https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--ic-doesnt-debug/poster.jpg?v=88213b034742 W10 · Production readiness: The person running the outage shouldn't touch the code https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--ic-doesnt-debug/video.mp4?v=88213b034742 66 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--mitigate-first Errors spike after a deploy. Don't hunt for the bug yet. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--mitigate-first/poster.jpg?v=e735938f57ad W10 · Production readiness: Errors spike after a deploy. Don't hunt for the bug yet. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--mitigate-first/video.mp4?v=e735938f57ad 71 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--own-the-outage Your payment provider broke checkout. Don't say so. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--own-the-outage/poster.jpg?v=f3e318180107 W10 · Production readiness: Your payment provider broke checkout. Don't say so. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--day-05-incident-management--own-the-outage/video.mp4?v=f3e318180107 75 yes monthly 0.5 https://www.himanshukukreja.in/learn/shorts/shorts--week-10-production-readiness-and-operational-excellence--week-10-preview--passed-the-tests It passed the tests. Now it's 3 AM and the pager is going off. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--week-10-preview--passed-the-tests/poster.jpg?v=dd78ca19c19f W10 · Production readiness: It passed the tests. Now it's 3 AM and the pager is going off. https://media.himanshukukreja.in/lectures/shorts--week-10-production-readiness-and-operational-excellence--week-10-preview--passed-the-tests/video.mp4?v=dd78ca19c19f 70 yes monthly 0.5 https://www.himanshukukreja.in/stories/hotstar-25-million-viewers-one-match 2026-10-16T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/crowdstrike-one-file-8-million-blue-screens 2026-10-16T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/irctc-tatkal-500-seats-2-million-users 2026-08-05T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/bridgelink-remote-android-testing 2025-11-27T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/ios-bridge-cross-platform-streaming 2025-08-15T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/digipin-scalable-location-service 2025-08-09T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/scalable-spam-detection-bloom-filter 2025-08-09T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/cdn-cache-poisoning-disaster 2025-08-08T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/integer-overflow-auto-increment-crisis 2025-08-08T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/leader-follower-replication-node-outages 2025-08-07T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/websockets-vs-webrtc-video-communication 2025-08-05T00:00:00.000Z monthly 0.7 https://www.himanshukukreja.in/stories/distributed-transactions-2pc-saga-pattern 2025-08-04T00:00:00.000Z monthly 0.7