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Tom Lane 798dabe838 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 19:24:46 -04:00
config Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
contrib Avoid memory leak on error while parsing pg_stat_statements dump file 2026-03-27 12:21:48 +02:00
doc doc: Improve description of pg_ctl -l log file permissions 2026-04-17 15:32:00 +09:00
src Fix relid-set clobber during join removal. 2026-04-20 19:24:46 -04:00
.abi-compliance-history Placate ABI checker. 2026-02-07 11:50:35 +13:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:03:27 -04:00
.cirrus.tasks.yml Fix typo 2026-01-07 15:49:00 +01:00
.cirrus.yml ci: Per-repo configuration for manually trigger tasks 2025-08-14 11:33:50 -04:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.git-blame-ignore-revs Add previous commit to .git-blame-ignore-revs. 2025-10-21 10:02:19 -05:00
.gitattributes Fix git whitespace warning 2025-08-15 10:31:52 +02:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
configure.ac Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
COPYRIGHT Update copyright for 2026 2026-01-01 13:24:10 -05:00
GNUmakefile.in Integrate pg_bsd_indent into our build/test infrastructure. 2023-02-12 12:22:21 -05:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Dynamically find correct installation docs in Makefile. 2022-01-19 14:48:25 +01:00
meson.build Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
meson_options.txt meson: Attach colon to keyword argument 2023-06-29 12:53:41 +02:00
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00

README 

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.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download/

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

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