[pgpool-general: 6837] Re: NOTIFY/LISTEN delay explanation?

[Tatsuo Ishii]

> Hi there,
> 
> Just installed PgPool 4.1.0 from sources today (with SSL
> enabled). Using it against PostgreSQL 12.1 on Arch Linux.
> 
> The PgPool configuration is a straight raw setup copied from the
> pgpool.conf.sample. Nothing fancy, just testing connection pooling.
> 
> Here is my question.
> 
> I have some rules in PG which respond to UPDATE/INSERT/DELETE to one
> particular table and send NOTIFY messages to connected apps. When all
> these apps are connected straight to Postgres (!), and some app is
> making changes to this table, then a NOTIFY is triggered and sent and
> received by all connected apps instantly. Literally, all happening at
> once.
> 
> However, if the same apps are connected to PgPool, instead of straight
> to Postgres, then there is a delay of about 3-5 seconds between making
> a modification and the reception of the database NOTIFY.
> 
> Now, from an app/deployment standpoint I am perfectly fine with that,
> but I would like to satisfy my curiosity as to WHY there is such a
> delay. I studied the config file settings, but I can not find any
> option that could relate to this and/or explain what is going on.
> 
> Anybody out there who can shed some light?

Interesting. Does it also happen if you try it using psql to LISTEN?

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp