pg_crdt VS cr-sqlite

Cool, I'll check out your repos. Supabase also as Postgres CRDT (https://github.com/supabase/pg_crdt).

But, in general, I think searching in and across documents and database storage is going to a thorny problem even with existing, hyper-optimized CRDT algorithms. For example, if you just store your Yjs document as a binary blob in a Postgres column, Postgres becomes the bottleneck and all the fancy range-tree or b-tree optimizations are no longer that helpful on the server. Plus, it'd be great to have an document edit just be a tiny insert into the database that can be streamed to other clients rather than a big row update.

This all may because the focus of CRDTs seems to be rooted in a fully decentralized, P2P system but many developers want collaborative text editing in a more traditional client-server model.

I'm part of the Supabase Realtime team. Thanks for doing this! We've been wanting to do it internally ever since launching Broadcast. We've also been experimenting with what a very integrated CRDT solution looks like (e.g. pg_crdt).

This is an experimental extension for CRDTs, `pg_crdt`[0]. It supports Yjs/Yrs and Automerge.

The linked blog post describes how we're thinking about this extension in a Supabase context. Ideally this "Show HN" generates some discussion/interest, both here and in the github discussions [1].

I want to emphasise this part from the blog post[2]: "pg_crdt has not been released onto the Supabase platform (and it may never be). We’re considering many options for offline-sync/support and, while CRDTs will undoubtedly factor in, we’re not sure if this is the right approach."

[0] GitHub repo: https://github.com/supabase/pg_crdt

[1] Discussions: https://github.com/supabase/pg_crdt/discussions

[2] Blog post: https://supabase.com/blog/postgres-crdt

I'm a happy user of https://github.com/vlcn-io/cr-sqlite/

If you're interested in this, here are some related projects that all take slightly different approaches:

- LiteSync directly competes with Marmot and supports DDL sync, but is closed source commercial (similar to SQLite EE): https://litesync.io

- dqlite is Canonical's distributed SQLite that depends on c-raft and kernel-level async I/O: https://dqlite.io

- cr-sqlite is a Rust-based loadable extension that adds CRDT changeset generation and reconciliation to SQLite: https://github.com/vlcn-io/cr-sqlite

Slightly related but not really (no multi writer, no C-level SQLite API or other restrictions):

- comdb2 (Bloombergs multi-homed RDMS using SQLite as the frontend)

- rqlite: RDMS with HTTP API and SQLite as the storage engine, used for replication and strong consistency (does not scale writes)

- litestream/LiteFS: disaster recovery replication

- liteserver: active read-only replication (predecessor of LiteSync)

Theory is great, but how can we apply this in practice? Instead of starting from 0, and writing a CRDT, let's try and leverage an existing project to do the heavy lifting. My choice is crSQLITE, an extension for SQLite to support CRDT merging of databases. Under the hood, the extension creates tables to track changes and allow inserting into an event log for merging states of separated peers.

Also https://github.com/vlcn-io/cr-sqlite/ which is SQLite + CRDTs

Runs/syncs to the browser too which is just lovely.

If you need multiple writers and can handle eventual correctness, you should really be using cr-sqlite[1]. It'll allow you to have any number of workers/clients that can write locally within the same process (so no network overhead) but still guarantee converge to the same state.

[1] https://github.com/vlcn-io/cr-sqlite

I am fully on the offline-first bandwagon after starting to use cr-sqlite (https://vlcn.io), which works similar to ElectricSQL.

I thought the bundle size of wasm-sqlite would be prohibitive, but it's surprisingly quick to download and boot. Reducing network reliance solves so many problems and corner-cases in my web app. Having access to local data makes everything very snappy too - the user experience is much better. Even if the user's offline data is wiped by the browser (offline storage limits are a bit of a minefield), it is straightforward to get all synced changes back from the server.

I didn't know that. Especially the first approach sounds interesting to me, because as far as I know the transactions of Yjs seem to be a problem on heavily changing documents. https://github.com/vlcn-io/cr-sqlite#approach-1-history-free... Thanks!

I wonder how this compares to https://vlcn.io?

The short ask: Anyone know of any projects that bring incremental view maintenance to SQLite?

The why:

Applications are usually read heavy. It is a sad state of affairs that, for these kinds of apps, we don't put more work on the write path to allow reads to benefit.

Would the whole No-SQL movement ever even have been a thing if relational databases had great support for materialized views that updated incrementally? I'd like to think not.

And more context:

I'm working to push the state of "functional relational programming" [1], [2] further forward. Materialized views with incremental updates are key to this. Bringing them to SQLite so they can be leveraged one the frontend would solve this whole quagmire of "state management libraries." I've been solving the data-sync problem in SQLite (https://vlcn.io/) and this piece is one of the next logical steps.

If nobody knows of an existing solution, would love to collaborate with someone on creating it.

[1] - https://github.com/papers-we-love/papers-we-love/blob/main/design/out-of-the-tar-pit.pdf