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From: Sami Imseih <[email protected]>
To: Lukas Fittl <[email protected]>
Cc: Michael Paquier <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Christoph Berg <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: ma lz <[email protected]>
Subject: Re: query_id: jumble names of temp tables for better pg_stat_statement UX
Date: Tue, 25 Mar 2025 09:59:34 -0500
Message-ID: <CAA5RZ0u7cV1gi_JSXKQ_yJD6FHBT3o9jrkp1rTgtcM-HPQJW8w@mail.gmail.com> (raw)
In-Reply-To: <CAP53PkzAPrHNHquT76mVjfStrz0B2hKhF+CbAZ_w9QJUJ_1oJQ@mail.gmail.com>
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> In my experience these often not work well with pg_stat_statements today because
> of their own bloat problem, just like with temp tables. You quickly have way too many
> unique entries, and your query text file accumulates a lot of duplicative entries
> (since the same query text gets repeated in the text file, since its queryid is different),
> to the point that you can't monitor your workload at all anymore.

That is true in terms of pg_stat_statements, and I have seen users
have to increase
pg_stat_statements.max to something much higher to avoid the bloat and constant
deallocs/GC.

But, besides pg_stat_statements, queryId is used to group queries for
database load
monitoring ( pg_stat_activity sampling). As of now, different schemas
are tracked
separately, but with this change they will be merged. This may come as
a surprise to
use-cases that rely on the existing behavior.

But I do agree that pg_s_s bloat is a big pain point, so this change
should be positive
overall. Let's see if there are enough complaints to force us to reconsider.


--
Sami Imseih
Amazon Web Services (AwS)






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