then the following two documents are both valid final states:
abc
acb
That's fine as long as you have an authoritative server that observes all events in a single order and a way to unwind misordered local state, but it means that it's not a CRDT.
Like Raft is a "special case" of Paxos, this feels like a "special case" of CRDT.
It has all the flavor of CRDT, but adds a leader and a different way for the total ordering (basically using leader's local lamport clock to break tie).
Throw in leader reelection and some ledger syncing and then give everything some other names, I bet you can have "collaborative text editing on one page".
Yeah. It’s also quite inefficient by default - because you’re storing deleted items and you have a uuid per character. And you usually want the other parts from a crdt which this discards. Like, a consistent ordering rule for siblings. Doing so barely adds any code (like 10 lines or so) and it makes the system way more useful.
I don’t really understand the benefit of doing this when text CRDTs are small, simple and fast.
> No; there is no single consistent final state that the system must converge to if the parts go offline.
Sounds like a naive implementation of delta state CRDT. I mean, what if the author has this major epiphany that it's nice to sync states to get convergence?
We could generalize having a tree of known authorities upstream with what a CRDT does, resulting in both being two special cases of a more general consistent event processing model. CRDT makes the order of events commutative, hence the "authority" becomes a property of the math itself, rather than a physical service.
