Count-min sketch.
also: count-min sketches · count min sketchA fixed-memory probabilistic counter that estimates per-key frequencies (never under-counting), used to spot hot keys in real time.
the two-minute refresher
- Exact per-key counting stores too much for high-traffic streams.
- A count-min sketch hashes each key into a few counter rows and takes the minimum.
- Estimates may over-count but never under-count, so no hot key is missed.
- Memory is fixed no matter how many distinct keys pass through.