pg_crdt VS crdt-benchmarks

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

Author of Yjs here. I'm all for faster data structures. But only benchmarking one dimension looks quite fishy to me. A CRDT needs to be adequate at multiple dimensions. At least you should describe the tradeoffs in your article.

The time to insert characters is the least interesting property of a CRDT. It doesn't matter to the user whether a character is inserted within .1ms or .000000001ms. No human can type that fast.

It would be much more interesting to benchmark the time it takes to load a document containing X operations. Yjs & Yrs are pretty performant and conservative on memory here because they don't have to build an index (it's a tradeoff that we took consciously).

When benchmarking it is important to measure the right things and interpret the results somehow so that you can give recommendations when to use your algorithm / implementation. Some things can't be fast/low enough (e.g. time to load a document, time to apply updates, memory consumption, ..) other things only need to be adequate (e.g. time to insert a character into a document).

Unfortunately, a lot of academic papers set a bad trend of only measuring one dimension. Yeah, it's really easy to succeed in one dimension (e.g. memory or insertion-time) and it is very nice click-bait. But that doesn't make your CRDT a viable option in practice.

I maintain a set of benchmarks that tests multiple dimensions [1]. I'd love to receive a PR from you.

[1]: https://github.com/dmonad/crdt-benchmarks

Diamond types author here! Congratulations on getting your crdt working! It’s lovely to see a new generation of CRDTs which have decent performance.

And nice stuff implementing peritext! I’d love to do the same in diamond types at some point. You beat me to it!

Im building a little repository of real world collaborative editing traces to use when benchmarking, comparing and optimising text based CRDTs[1]. The automerge-perf editing trace isn’t enough on its own. And we’re increasingly converging on a format for multi user concurrent editing traces too[2]. It’d be great to add some rich text editing traces in the mix if you’re interested in recording something, so we can also compare how peritext performs in different systems.

Anyway, welcome to the community! Love to have more implementations around!

https://github.com/josephg/crdt-benchmarks

https://github.com/dmonad/crdt-benchmarks/issues/20

So yes, a particularly large document is not the norm but it can happen.

JavaScript CRDTs can be quite performant, see the Yjs benchmarks: https://github.com/dmonad/crdt-benchmarks