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Comment by sho | Hacker News Reader

Be interested to hear a comparison between this lib and litestream/litefs, which seem to be actively developed by fly.io for a similar use case

https://litestream.io/ https://github.com/superfly/litefs

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Litestream/LiteFS author here. It's been a while since I looked at Mycelial but IIRC it does eventually consistent replication using CRDTs. That's great for systems that need multi-master but there are consistency tradeoffs that you have to watch out for.

Litestream & LiteFS are both physical, async replication tools so they actually work at the page level. When a transaction commits, the changed pages are shipped off to a replication destination. By replaying those changes in the same order, you can rebuild the current state of the database (or any point-in-time state in between). Both of these systems require a single primary node at a time so multi-master doesn't work with them.

Litestream only replicates to "dumb storage" (e.g. S3, SFTP) whereas LiteFS replicates to other live nodes so you can have live replicas.

cr-sqlite [0] is another option. It has the added benefit of being able to run in the browser (persisting to IndexedDB a la absurd-sql, though it uses a fork of wa-sqlite [1]). In theory it could also persist to the Origin Private Filesystem via SQLite's official impl, though switching doesn't seem to be strictly better [2]. A con is that it doesn't enforce foreign key constraints (though of course you can still do joins). Cr-sqlite also has better documentation about what CRDTs it supports than Mycelite [3], which is something I brought up in a recent thread [4](which might have triggered this post). I'm personally using cr-sqlite in an Anki clone I'm building [5] and have only positive things to say about cr-sqlite and its maintainer.

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

[1] https://github.com/rhashimoto/wa-sqlite/

[2] https://github.com/rhashimoto/wa-sqlite/discussions/63

[3] https://github.com/vlcn-io/cr-sqlite/#how-does-it-work

[4] https://news.ycombinator.com/item?id=36473772

[5] https://github.com/AlexErrant/Pentive

Thank you for the link, very interesting. A lot of work going on in this space right now!

Litestream lets you pick which servers you replicate your data to.

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