rdts.datatypes

An EWFlag (Enable-Wins Flag) is a Delta CRDT modeling a boolean flag.

When the flag is concurrently disabled and enabled then the enable operation wins, i.e. the resulting flag is enabled.

A GCounter is a Delta CRDT modeling an increment-only counter.

A LastWriterWins (register) is a common fallback for datatypes that don’t have good merge semantics.

Concurrent writes are resolved by a causality preserving clock based on milliseconds, using a random value as a tie breaker. The random values are non-fair, so a specific replica is more likely to win.

An MultiVersionRegister (Multi-Value Register) is a Delta CRDT modeling a register.

In the absence of concurrent writes, the MultiVersionRegister is either empty or holds one value. When multiple values are written concurrently, reading the MultiVersionRegister returns a set holding all these values.

A PNCounter (Positive-Negative Counter) is a Delta CRDT modeling a counter.

It is composed of two grow-only counters (see GrowOnlyCounter) to enable both increments and decrements of the counter value.

A set that allows deletes. Each unique element tracks the dots of when it was inserted. Removals do not override concurrent inserts.