CRDT Types

Data types that are called CRDT which is either Conflict-free Replicated Data Type or Commutative Replicated Data Types are used in lattices.

Available types:

counter

ever-increasing counter

// some initial value
{"user_visits_counter": 1}
// next value
{"user_visits_counter": 2}

// on update this value will be ignored
{"user_visits_counter": 1}

set

set of some elements, the set can only grow (new elements added) and elements can never be deleted from the set

{"last_message_set": [1, 12, 13465]}

// on update -- will have no effect
{"last_message_set": [1, 12]}

register

a value with a timestamp or a version, which is updated with last-write-wins (LWW) semantics. Any valid json might be used as a value.

{"status_register": [1, {"icon": "busy", "message": "working"}]}
// next value
{"status_register": [2, {"icon": "ready_for_chat", "message": "???"}]}

// on update -- will have no effect
{"status_register": [1, {"icon": "offline", "message": "disconnected"}]}

{"another_register": [1503339804.859186, "hello_string"]}

Note

Only non-negative values might be used as a version. Both integers and floating point number are okay, but value will be treated