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Date: Thu, 21 Aug 2025 11:17:27 -0700
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Subject: Re: Streaming replica hangs periodically for ~ 1 second - how to
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To: depesz@depesz.com
Cc: PostgreSQL General <pgsql-general@lists.postgresql.org>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
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On 8/21/25 09:51, hubert depesz lubaczewski wrote:
> On Thu, Aug 21, 2025 at 08:59:03AM -0700, Adrian Klaver wrote:
>> Getting to the bottom of the bag of ideas:
>> Have you looked at the OS system log for the time period involved?
> 
> Yes. Mostly dmesg. Nothing interesting logged around the time.
> 
>> You mentioned this seemed to involve PREPARE and DISCARD ALL.
>> Is this the same set of statements or is it all over the place?
> 
> No. From what I can tell it's random sample.
> 
>> Also it would be helpful to know what bouncer you are actually using and
>> what mode you are running in?
> 
> pgBouncer, version 1.23.1. As for more... mostly transaction pooling.
> Applications go using transaction pooling, but people (dbas, ops) have
> session pooling.

Have you looked at?:

https://www.pgbouncer.org/changelog.html#pgbouncer-124x

To see if anything stands out.

Then there is:

https://www.pgbouncer.org/config.html#max_prepared_statements

The below may also be worth looking at:

https://github.com/pgbouncer/pgbouncer/pull/1144

I can't help thinking that there is a caching issue at stake, though 
that is just a guess.


> 
> Best regards,
> 
> depesz
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com