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Tom Lane f0ac6d494b Fix relid-set clobber during join removal. 
Commit cfcd57111 et al fell over under Valgrind testing.
(It seems to be enough to #define USE_VALGRIND, you don't actually
need to run it under Valgrind to see failures.)  The cause is that
remove_rel_from_eclass updates each EquivalenceMember's em_relids,
and those can be aliases of the left_relids or right_relids of some
RestrictInfo in ec_sources.  If the update made em_relids empty then
bms_del_member will have pfree'd the relid set, so that the subsequent
attempt to clean up ec_sources accesses already-freed memory.

We missed seeing ill effects before cfcd57111 because (a) if the
pfree happens then we will remove the EquivalenceMember altogether,
making the source RestrictInfo no longer of use, and (b) the
cleanup of ec_sources didn't touch left/right_relids before that.

I'm unclear though on how cfcd57111 managed to pass non-USE_VALGRIND
testing.  Apparently we managed to store another Bitmapset into the
freed space before trying to access it, but you'd not think that would
happen 100% of the time.  I think what USE_VALGRIND changes is that it
makes list.c much more memory-hungry, so that the freed space gets
claimed by some List node before a Bitmapset can be put there.

This failure can be seen in v16, v17, and master, but oddly enough not
v18.  That's because the SJE patch replaced the simple bms_del_members
calls used here with adjust_relid_set, which is careful not to
scribble on its input.  But commit 20efbdffe just recently put back
the old coding and thus resurrected the problem.

Discussion: https://postgr.es/m/458729.1776724816@sss.pgh.pa.us
Backpatch-through: 16, 17, master
2026-04-20 19:24:52 -04:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Update config.guess and config.sub 2026-04-09 11:26:14 +02:00
contrib pg_plan_advice: pgindent 2026-04-17 17:46:27 -04:00
doc doc: Fix missing role attribute in pg_get_tablespace_ddl() description. 2026-04-20 13:31:13 -07:00
src Fix relid-set clobber during join removal. 2026-04-20 19:24:52 -04:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:09:34 -04:00
.cirrus.tasks.yml Enable test_cplusplusext with MSVC 2026-04-01 07:48:47 +02:00
.cirrus.yml ci: Per-repo configuration for manually trigger tasks 2025-08-14 11:54:03 -04:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Update .editorconfig and .gitattributes for postgresql.conf.sample. 2025-11-18 10:28:36 -06:00
.git-blame-ignore-revs Add a couple of commits to .git-blame-ignore-revs. 2026-04-08 13:41:22 -05:00
.gitattributes Update .editorconfig and .gitattributes for postgresql.conf.sample. 2025-11-18 10:28:36 -06:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
.mailmap Add a Git .mailmap file 2024-11-05 13:56:02 +01:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Add errdetail() with PID and UID about source of termination signal. 2026-04-07 10:22:33 -04:00
configure.ac Add errdetail() with PID and UID about source of termination signal. 2026-04-07 10:22:33 -04:00
COPYRIGHT Update copyright for 2026 2026-01-01 13:24:10 -05:00
GNUmakefile.in Allow selecting the git revision to be packaged by "make dist". 2024-05-03 11:08:50 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Restore AIX support. 2026-02-23 13:34:22 -05:00
meson.build Meson: Fix check_header() for readline and gssapi 2026-04-20 12:36:14 +09:00
meson_options.txt Revert "Add built-in fuzzing harnesses for security testing." 2026-04-10 09:53:58 -04:00
README.md Revise the style of a paragraph in README.md. 2024-03-21 10:16:41 -05:00

README.md

PostgreSQL Database Management System

This directory contains the source code distribution of the PostgreSQL database management system.

PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.

Copyright and license information can be found in the file COPYRIGHT.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.

The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.