[pgpool-general: 8714] Re: what is pgpool-II "extensions" RPM package used for?

[zam bak]

On Mon, Apr 3, 2023 at 9:26 PM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
>
> >> pgpool-II-pg*-extensions packages are used for online recovery.
> >> If you are using only connection pooling and load balancing,
> >> you don't need this package.
> >
> > Thanks for explaining.
> > What exactly includes "online recovery"? Is it in the docs or..?
> > Is this any functionality where primary and replicas are set as
> > backend_flag0 = 'ALWAYS_PRIMARY'
> > backend_flag1 = 'DISALLOW_TO_FAILOVER'
> >
> > I think it would be very beneficial to update docs and state in which
> > cases extensions are required.
> > This is useful in situations where PgPool is installed on a different
> > server than PostgreSQL.
>
> I thought it is pretty obvious that you do not need to install the
> extensions on the server on which only Pgpool-II runs, because
> extensions can only be executed by PostgreSQL.

No, my question was for the opposite scenario
Of course one would not need to install extensions on the PgPool
server but only on the PostgreSQL server.
That part is clear.
However, even installing extensions on PostgreSQL server seems to be
optional based on which features of PgPool are being used.
As Bo Peng pointed out, only if you use "online recovery" you need to
install extensions on PostgreSQL server.
I was just asking to perhaps update docs/clarify for which pgpool
features is extensions package mandatory to be installed on PostgreSQL
server

>
> > In those cases, users may then decide to not install extensions on
> > PostgreSQL servers
>
> I'm confused. Why do you think so?

I hope my comment above clarifies it.
But to add more context - In a lot of shops, installing additional
packages in the production environment has to be justified.
For the scenario I described (separate PgPool server and separate
PostgreSQL servers), extension package seems not necessary (based on
pgpool features used)
Also, providing a link to documentation eases that process when a
package is needed.
Hope that helps.



>
> Best reagards,
> --
> Tatsuo Ishii
> SRA OSS LLC
> English: http://www.sraoss.co.jp/index_en/
> Japanese:http://www.sraoss.co.jp