Re: unstable query plan on pg 16,17,18
Attila Soki <atiware@gmx.net>
From: Attila Soki <atiware@gmx.net>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: pgsql-performance@postgresql.org,
Laurenz Albe <laurenz.albe@cybertec.at>
Date: 2026-02-24T11:37:17Z
Lists: pgsql-performance
On 24 Feb 2026, at 12:09, Andrei Lepikhov <lepihov@gmail.com> wro > This update gives us more useful details. In PG14, the join search problem involved at most 9 relations. In PG19, the maximum is now 18 joins. Do you know what your join_collapse_limit is set to? It looks like subplan pull-ups have made things more complex. > First, we should look into any possible 'rescan cost' issues on our side as developers. > On your end, please check the join_collapse_limit setting. If needed, try increasing it to around 20. This might help. join_collapse_limit is not set, so it is the default, 8 I will try if something around 20 helps. thanks btw: I working on providing more details to the query regards, Attila