From: Tom Lane <tgl@sss.pgh.pa.us>
To: Lowell Hought <lowell.hought@gmail.com>
cc: Laurenz Albe <laurenz.albe@cybertec.at>, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18950: pgsql function that worked in Postgresql 16 does not
 return in Postgresql 17
In-reply-to: 
 <CAJtAGPpa4yYS6LLO5RHzwe9q7NpHiuuvEX1wVtErpie3EBWZJQ@mail.gmail.com>
References: <e9eb5136fb60188fc61c110e9706709fc13638e0.camel@cybertec.at>
 <75D714EA-CD1E-4F80-A2E8-29E378EC2200@gmail.com>
 <81946.1749348479@sss.pgh.pa.us>
 <CAJtAGPpa4yYS6LLO5RHzwe9q7NpHiuuvEX1wVtErpie3EBWZJQ@mail.gmail.com>
Comments: In-reply-to Lowell Hought <lowell.hought@gmail.com>
	message dated "Sat, 07 Jun 2025 21:57:27 -0500"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <88315.1749351768.1@sss.pgh.pa.us>
Date: Sat, 07 Jun 2025 23:02:48 -0400
Message-ID: <88316.1749351768@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/88316.1749351768%40sss.pgh.pa.us>
Precedence: bulk

Lowell Hought <lowell.hought@gmail.com> writes:
> Yes!  I just changed the parameter as  you suggested and the query returned
> as expected.
> So I guess something changed between version 16 and version 17?  Perhaps
> the default for that setting?

No, that default has not changed.  What apparently happened is that
cost estimates or something changed enough to persuade the planner
to use a generic plan that's considerably inferior to what it was
choosing before.  There's nowhere near enough info in your report
to pin it down more closely than that.

Just to eliminate the obvious --- you did run ANALYZE after the
upgrade, right?  If you had any nondefault settings of
default_statistics_target or similar planner parameters,
did you make sure they got transferred to the new installation?

			regards, tom lane