From: Richard Guo <rguo@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix semijoin unique-ification for child relations
Date: Fri, 29 Aug 2025 04:14:40 +0000
Message-ID: <E1urqVb-002Aki-2w@gemulon.postgresql.org> (raw)
Fix semijoin unique-ification for child relations
For a child relation, we should not assume that its parent's
unique-ified relation (or unique-ified path in v18) always exists. In
cases where all RHS columns that need to be unique-ified are equated
to constants, the unique-ified relation/path for the parent table is
not built, as there are no columns left to unique-ify. Failing to
account for this can result in a SIGSEGV crash during planning.
This patch checks whether the parent's unique-ified relation or path
exists and skips unique-ification of the child relation if it does
not.
Author: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/CAMbWs49MOdLW2c+qbLHHBt8VBu=4ONpM91D19=AWeW93eFUF6A@mail.gmail.com
Backpatch-through: 18
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/97b0f36bde9a08bc6f004438ff8fc0afbcb418c0
Modified Files
--------------
src/backend/optimizer/plan/planner.c | 9 ++++++
src/test/regress/expected/join.out | 60 ++++++++++++++++++++++++++++++++++++
src/test/regress/sql/join.sql | 37 ++++++++++++++++++++++
3 files changed, 106 insertions(+)
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To: pgsql-committers@postgresql.org
Cc: rguo@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix semijoin unique-ification for child relations
In-Reply-To: <E1urqVb-002Aki-2w@gemulon.postgresql.org>
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