From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
cc: Christoph Berg <myon@debian.org>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        ma lz <ma100@hotmail.com>
Subject: Re: query_id: jumble names of temp tables for better pg_stat_statement UX
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Comments: In-reply-to Michael Paquier <michael@paquier.xyz>
	message dated "Sat, 22 Mar 2025 19:32:47 +0900"
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Date: Sat, 22 Mar 2025 11:12:39 -0400
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Michael Paquier <michael@paquier.xyz> writes:
> On Sat, Mar 22, 2025 at 10:43:00AM +0100, Christoph Berg wrote:
>> Are we at the point where the patch is already Ready for Committer?

> I'll think a bit more about how to document all that.  Anyway, yes,
> I'm OK with the per-field custom_query_jumble, so let's move on with
> that, so I will do something about that.

I'm not terribly happy with the entire proposal.

(1) I know it was asserted upthread that there was no performance
impact, but I find that hard to believe.

(2) This patch inserts catalog lookups into query ID computation,
which AFAIK there never were before.  This means you can't compute a
query ID outside a transaction or in an already-failed transaction.
Surely that's going to bite us eventually.

(3) I think having query jumbling work differently for temp tables
than other tables is a fundamentally bad idea.

So my feeling is: if we think this is the behavior we want, let's do
it across the board.  I suggest that we simply drop the relid from the
jumble and use the table alias (that is, eref->aliasname) instead.
ISTM this fits well with the general trend in pg_stat_statements
to merge statements together more aggressively than the original
concept envisioned.

			regards, tom lane