I want to migrate my Nextcloud instance from MariaDB over to PostgreSQL. I already have a PostgreSQL service running for Lemmy. And I’m pretty starved for RAM.
Would it be better to just have one PostgreSQL service running that serves both Nextcloud and Lemmy? Or should every service have its own PostgreSQL instance?
I’m pretty new to PostgreSQL. But in my mind I would tend towards one service to serve them all and let it figure out by itself how to split resources between everything. Especially when I think that in the long run I will probably migrate more services over to PostgreSQL (and upgrade the RAM).
But maybe I am overlooking something.
Edit: Thanks guys, I’ve settled for a single instance for now. And after a little tuning everything seems to be running better than ever, with room to spare.
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If you’re the only user and just want it working without much fuss, use a single db instance and forget about it. Less to maintain leads to better maintenance, if performance isn’t more important.
It’s fairly straightforward to migrate a db to a new postgres instance, so you’re not shooting yourself in a future foot if you change your mind.
Use PGTune to get as much as you can out of it and adjust if circumstances change.
It’s fairly straightforward to migrate a db to a new postgres instance, so you’re not shooting yourself in a future foot if you change your mind.
That’s what I needed to hear. I’ll just try it out and see what works best for me. Stupid me didn’t even think of that.
I’m not really bothered about services going down all at once. The server is mostly just used by me and my family. We’re not losing money if it’s out for an hour or so.
In a hobby it’s easy to get carried away into doing things according to “best practices” when it’s not really the point.
I’ve done a lot of redundant boilerplate stuff in my homelab, and I justify it by “learnding”. It’s mostly perfectionism I don’t have time and energy for anymore.
Would it be better to just have one PostgreSQL service running that serves both Nextcloud and Lemmy
Yes, performance and maintenance-wise.
If you’re concerned about database maintenance (can’t remember the last time I had to do this… Once every few years to migrate postgres clusters to the next major version?) bringing down multiple services, setup master-slave replication and be done with it
There are pros and cons to each…
There’s the question of isolation. One shared service going down brings down multiple applications. But it can be more resource efficient to have a single DB running. If you’re doing database maintenance it can also be easier to have one instance to tweak. But if you break something it impacts more things…
Generally speaking I lean towards one db per application. Often in separate containers. Isolation is more important for what I want.
I don’t think anyone would say you’re wrong for using a single shared instance though. It’s a more “traditional” way of treating databases actually (from when hardware was more expensive).
i like to have them separated by service, i have 3/4 dbs running, at least 2 of them are postgreSQL.
Native, docker, something else? How starved are you at the moment?
If I went with a shared service I would run it natively on Debian Stable.
Lemmy currently uses a dockerised PostgreSQL service. I’ve got 16 GB RAM which is currently mostly occupied by both MariaDB and the PostgreSQL Docker.
Have you tried limiting the RAM usage of those containers? They tend to use as much as you give them, which is all of it by default.
That was more or less the default of the PostgreSQL container and it ran like ass because I don’t have a SSD.
Basically I had to give MySQL a ton of RAM for Nextcloud and PostgreSQL for Lemmy. For now I’ve put both on the same PostgreSQL instance and let them battle out who gets the assigned RAM by themselves.
