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Comment by gagik_co | Hacker News Reader

This is impressive! After Realm depreciation I have been trying many different offline sync options, they are especially few on Dart… Dart-Rust binding generator is pretty great though so it’s nice this is in Rust. Will keep an eye on this.

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Thanks! Yeah, Realm's shift in direction left a gap in the offline-first space.

I didn't build Dart bindings yet (Rust → WASM → TypeScript for v0.1.0), but since the core is in Rust, Dart bindings via dart_rust_bridge are definitely feasible. Would actually be a great addition.

Are you actively looking for a Realm replacement for a Dart project? Curious what your offline sync requirements are. It might help me prioritize Dart support

I use Loro CRDT, which is written in Rust as well, on my Dart apps with flutter_rust_bridge and it works pretty well. For syncing I'm using their Loro protocol product although I used iroh before. However, the annoying thing about how the CRDT libraries work is that they're essentially key value NoSQL type storage, not relational. I would love something like SQLite or Postgres on both the server and client that can sync, which companies like ElectricSQL have, but no Dart bindings and also I'd prefer to be in the all Rust ecosystem as well as self host.

This is a write up that may be helpful for you: https://sqlsync.dev/posts/stop-syncing-everything/

You've hit on the core limitation because SyncKit has the same issue. Document/key-value like Loro and Yjs. The relational model problem is fundamental to CRDTs. They guarantee conflict-free convergence because documents are independent, but that breaks with foreign keys and joins. Can't have arbitrary SQL queries and guaranteed convergence without coordination.

ElectricSQL and PowerSync solve it differently (full SQL but weaker offline guarantees). For SyncKit, document-based state is an architectural choice, not something v0.2.0 will change.

I'm curious to know how you're working around this with Loro. Are you building your own query layer or are you keeping everything denormalized?

Yeah I'm essentially writing my own ORM with functions like getFoo which queries the exact substructure of the CRDT to find the info I need. Apparently Postgres is getting a CRDT extension though but we'll see how it goes, typically it's not that fast.

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