On Thu, Apr 6, 2023 at 11:13 PM Tatsuo Ishii <ishii@xxxxxxxxxxxx> wrote: > I am welcome you to > join and continue the discussion on pgpool mailing list. I truly believe that this problem – HA – is PostgreSQL's, not 3rd party's. And it's a shame that Postgres itself doesn't solve this. So we're discussing it here. > > What if pg1 is currently primary, pg0 is standby, both are healthy, but > > due not network issues, both pg1 and w2 are not reachable to other > > nodes? Will pg1 remain primary, and w0 and w1 decide to promote pg0? > > pg1 will remain primary but it is set to "quarantine" state from > pgpool's point of view, which means clients cannot access pg1 via > pgpool. So we have a split brain here – two primaries. Especially if some clients communicate with PG directly. And even if there are no such clients, archive_command is going to work on both nodes, monitoring will show two primaries confusing humans (e.g, SREs) and various systems, if we have many standby nodes, some of them might continue replicating from the old primary if they happen to be in the same network partition, and so on. I don't see how all these things can be solved with this approach.
