Re: Is there value in having optimizer stats for joins/foreignkeys?

From: Alexandra Wang <alexandra(dot)wang(dot)oss(at)gmail(dot)com>
To: pgsql-hackers(at)lists(dot)postgresql(dot)org
Cc: Tomas Vondra <tomas(at)vondra(dot)me>, Andrei Lepikhov <lepihov(at)gmail(dot)com>, Corey Huinker <corey(dot)huinker(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, hs(at)cybertec(dot)at, Jeff Davis <pgsql(at)j-davis(dot)com>
Subject: Re: Is there value in having optimizer stats for joins/foreignkeys?
Date: 2026-04-29 13:08:58
Message-ID: CAK98qZ0Vr4D3usesj_qpNFAH1=7NKX=bR9bNRNM7tdnk5KWHDw@mail.gmail.com
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On Tue, Apr 28, 2026 at 10:59 PM Alexandra Wang <
alexandra(dot)wang(dot)oss(at)gmail(dot)com> wrote:
> I've attached the v1 patch and am looking for reviews.

Sorry for the CI breakage!

The Assert(ndims >= 2) in multi_sort_init() failed for join stats that
have a single filter column. Attached v2 that fixed it (relaxed to
ndims >= 1, plus a shadowed variable warning from GCC).

The pg_upgrade failure is expected due to the new catalog columns.
I will post a fix soon.

Best,
Alex

Attachment Content-Type Size
v2-0001-Add-join-MCV-statistics-for-selectivity-estimatio.patch application/octet-stream 217.0 KB

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