[pgpool-general: 7649] Re: Can PGPool manage multiple Postgres Clusters on every node?

[Luca Maranzano]

Hi Tatsuo, thank you for your feedback.

The main requirement is to separate the 4 PG instances on every node,
mainly for performance and management reasons.

So it seems that the only solution is to have 4 pgpool instances for every
node, right?

Thanks
Best regards
Luca



On Mon, Jul 26, 2021 at 3:56 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:

> > Hello,
> >
> > we are setting up a 3 nodes clusters similar to this one:
> >
> > https://www.pgpool.net/docs/latest/en/html/example-cluster.html
> >
> > we are using CentOS 7.9 physical nodes with PGPool 4.2 and PostgreSQL 12.
> >
> > We need to have on every node 4 PostgreSQL instances (1 for prod, 1 for
> > pre-production, 1 for test and 1 for dev), all of them must be in
> streaming
> > replication with the other 2 nodes.
> >
> > Can PGPool manage such configuration? From the documentation we didn't
> find
> > any reference.
> > We are thinking to create 4 different pgpool instances, each one with its
> > set of files and tcp port, is this a supported configuration?
>
> The short answer is no.
>
> Pgpool-II assumes that there's only one streaming replication primary
> server exists among PostgreSQL instances. That means:
>
> Suppose you have following PostgreSQL instances:
>
> "A" group for "prod": A1, A2, A3
>
> Pgpool-II can manage A1, A2 and A3, assuming that one of A1, A2,
> A3 is the primary server and rest of it are standby servers.
>
> Similary:
> "B" group for "pre-production": B1, B2, B3
>
> Pgpool-II can manage B1, B2 and B3, assuming that one of B1, B2,
> B3 is the primary server and rest of it are standby servers.
>
> *BUT* a Pgpool-II instance cannot manage A group and B group altogeter
> at the same time.
>
> So it seems you have 4 groups of PostgreSQL instances (prod,
> pre-production, test and dev), you can manage each group by assigning
> 4 Pgpool-II instances to each. In this case each Pgpool-II instance is
> completely separated and will not communicate each other. I am not
> sure what you can achieve in this configuration.
>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
>
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