Re: Squash constant lists in query jumbling by default - Mailing list pgsql-hackers

From Dmitry Dolgov
Subject Re: Squash constant lists in query jumbling by default
Date
Msg-id CA+q6zcVTK-3C-8NWV1oY2NZrvtnMCDqnyYYyk1T7WMUG65MeOQ@mail.gmail.com
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In response to Re: Squash constant lists in query jumbling by default  (Álvaro Herrera <alvherre@alvh.no-ip.org>)
Responses Re: Squash constant lists in query jumbling by default
Re: Squash constant lists in query jumbling by default
List pgsql-hackers

On Tue, Mar 25, 2025, 6:28 PM Álvaro Herrera <alvherre@alvh.no-ip.org> wrote:
On 2025-Mar-25, Tom Lane wrote:
> If this GUC sticks around, it should be at least PGC_SUSET (on
> the analogy of compute_query_id) to make it harder to break
> pg_stat_statements that way.

I have no problem making it superuser-only, and I can see making "on" be
the default.  I am not opposed to removing it completely either, if we
really think that the current behavior is no longer useful for anybody.

I'm in favor of removing the GUC of course, but if memory serves there
were some folks in the patch discussion thread, who claimed they would
need to be able to keep non-squashed behavior. I don't recall if there were
particular arguments to support that, will try to find those messages again.
But overall as long as nobody objects, I think it's fine to get rid of GUC.

Earlier in the discussion, other possible values for the option were
suggested, such as a way to distinguish arrays that had "lots" (say,
hundreds or more) of entries from arrays that were "small".  That could
be selected by the user (or site admin) using this GUC, though there was
no agreement on exactly what that would be.  During the FOSDEM 2024
development meeting there was a general dislike of this idea, which
AFAIR was mostly predicated on the displayed query no longer being valid
SQL.  But now that we've chosen a format that uses SQL comments, this is
no longer a problem, so I think we haven't closed that door yet.  But we
may still find out that no user cares about this.

Agree, the way how things work now brings this option back on the table.
I can refresh the patch doing this, but I'm afk for about a week so it will
take some time. At the same time the proposal to do squashing by default
does not seem to be strictly dependent on that, so maybe they could be
considered as isolated ideas.

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