cross-posted from: https://lemmy.ml/post/1374138
I’m thinking about setting up my own (bare metal) Lemmy instance to play around with it, but it seems to require PostgreSQL. Everything else on my system uses MySQL, and I don’t really want to run 2 separate database services. I guess I would also be fine with using an SQLite file, but that’s not ideal.
Has anyone managed to set up a Lemmy instance with MySQL instead of PostgreSQL? Are you aware of any PostgreSQL to MySQL or SQLite compatibility layers?
Lemmy is implemented in Rust using the Diesel ORM/Query Builder for persistence. I don’t know enough rust to comment specifically, but based on my knowledge of other ORMs and stuff it should be possible to support different database backends, but it would likely not “just work” without some effort on the part of the developers.
One of the things that is being done for the next release is a bunch of pg optimization work, which to me makes it even less likely for it to work with minimal changes, as they are likely putting in some amount of postgres-specific code to achieve those gains.
Diesel supports mysql/Maria but meanwhile lemmy itself assumes it will be psql & I agree that changing that esp after 0.18 would be a silly idea. Changing it to support clickhouse or bigtable/c*/dynamo also a silly idea but maybe more worthwhile than mysql.
I personally would love to see Cockroach support, as that is still a dialect of pg but often takes some work to get running right/well/at all.
They are not really interchangeable… They are intended for different use cases.
And I’m pretty ready to bet that using any kind of bodged together compatibility-anything would be a lot more complex than just setting up postgres to begin with.
I did for my matrix instance, and its bridges, it wasn’t complicated.
Only PostgreSQL at the moment. I also don’t believe it currently supports SSL connection to Postgres so you’ll want to run it on the same machine or have a tunnel to your DB.
There is zero chance you’ll get it running on anything else without significant code change.
Diesel, the ORM package used by Lemmy, does have a MySQL backend, but all of the database migrations and performance considerations factored into the schema design are specifically written for PostgreSQL. It would be an absolutely massive undertaking to change this. It would be easier to create an entirely new threadiverse application from scratch.
