The write side on the client can't be transparent, can it?

Otherwise either write persistence is best-effort, writes don't work offline at all, or there is some kind of custom conflict resolution layer that guarantees that all writes will be accepted, like CRDTs

Right, it isn’t transparent. Unlike a CRDT, not every write is guaranteed to be accepted. Every write is applied locally at once, durably queued, and sent to PostgreSQL when online. The guarantee is that no write is lost, and each one ends with an explicit verdict: accepted, or refused with the reason and rolled back locally.

What happens after the first write then? Is the whole sequence dropped as soon as one write is rejected?

Is this like ElectricSQL which was acquired recently?

How do you handle syncing? Due to not many good options I resorted to putting a CRDT in my database on client and server side and then running their sync functions on every change but I wish Postgres had integrated CRDTs.

Thanks. Yeah there's always LWW but modern CRDT libraries are way more advanced than that including intelligent merges so wondering if there was something closer to that in Postgres. By the way all your comments are showing up as dead which I have to vouch.

CRDT is useful when the application has a meaningful way to merge concurrent edits, if any. They don' replace database constraints or business rules. With LWW, you have a predictable winner when 2 devices replace the same value. Merging changes does not automatically preserve a unique realist: you need server validaation. LWW loses concurrent intents, but for many PG-backed applications, explicit/nderstandable conflict outcomes matters more than automatic edits preservation. BTW, what do you mean by dead comments?

Your comments don't actually show up, they're all flagged by default. I think you're shadowbanned, maybe email [email protected] to get it sorted out.

And yes I know all about business rules, but for my apps I need CRDTs which work as required for my business logic. LWW is not sufficient for me.

I understand. I needed rules, so LWW like Cassandra covered probably 80% of use cases. Otherwise, it is like Electric, all left to you.

FYI, I added CDRT support (the same as PowerSync) and an example. It is agnostic, so you bring in your prefered library. It is not optimal though, I don't clean Postgres. I will push this.

Thanks I'll look into it.