CRDT.
also: CRDTs · conflict-free replicated data type · conflict-free replicated data types · G-Counter · PN-Counter · OR-SetA data structure replicas update independently and merge automatically, with merges that are commutative, associative and idempotent.
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- Merge order doesn't matter, so all replicas converge without coordination.
- G-Counter: one counter per node, value = sum. PN-Counter: one for +, one for −.
- OR-Set: add and remove elements, add wins over a concurrent remove (shopping carts).
- Costs: extra metadata, tombstones, and only operations that fit the type.