Re: Can logical replication be a solution to my current MariaDB/Galera setup?

Am 22.05.26 um 15:18 schrieb Michael Grimm:
> I have never run a postgres server before, but I do run a mariadb
> galera cluster [1] for storing emails by an IMAP server [2].
> Distribution and failover is dealt by haproxy [3]. This mail server
> setup has to deal with less than 250 mails a day, a database size of
> under 6 GB, and a handful of users. You see, that this system is
> bored to death ;-)
>
> I have read a lot about replication in order to find something
> comparable to a galera cluster with its multi master capabilities.
> Now, I have learned that multi master can only be achieved by using
> third party plugins. Not all of those are available for my FreeBSD
> systems, though.
>
> As a newbie I do currently tend to use logical replication with
> mutual publish and subscribe instead, either by pglogical2 or "self-
> made". I am in the -probably naive- impression that this could work.
> As before, failover will be handled by haproxy by simply directing
> read/write access to another postgres node available. When a failed
> node will become online again, logical replication should enable
> this node to recover, right?
>
> Here are my questions:
>
> #) Is this feasible or nonsense?
> #) What would an alternatives for FreeBSD be (pgpool-II, repmgr, …)?

For such a system I don't see the need for a multi-master setup (neither
with Postgres nor with MariaDB).

That's typically used if you need to spread the write load across nodes,
quite frequently because access is geographically distributed and the
latency is not acceptable.

For high availability you don't need multi-master. A standard
streaming replication with a failover mechanism is completely enough
in my opinion.