Re: Patroni vs pgpool II

Tatsuo Ishii <ishii@sraoss.co.jp>

From: Tatsuo Ishii <ishii@sraoss.co.jp>
To: ronljohnsonjr@gmail.com
Cc: pgsql-general@lists.postgresql.org
Date: 2023-04-07T12:10:42Z
Lists: pgsql-general
> Scenario:
> S0 - Running Postgresql as primary, and also PgPool.
> S1 - Running Postgresql as secondary, and also PgPool.
> S2 - Running only PgPool.  Has the VIP.
> 
> There's no /need/ for Postgresql or PgPool on server 0 to shut down if
> it loses contact with S1 and S2, since they'll also notice that that
> S1 has disappeared.  In that case, they'll vote S1 into degraded
> state, and promote S1 to be the Postgresql primary.
> 
> A good question is what happens when S0 and S1 lose connection to S2
> (meaning that S2 loses connection to them, too).  S0 and S1 then
> "should" vote that S0 take over the VIP.  But, if S2 is still up and
> can connect to "the world", does it voluntarily decide to give up the
> VIP since it's all alone?

Yes, because S2 pgpool is not the leader anymore. In this case S2
voluntarily gives up VIP.

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