Michael Paquier dcdc95cb4d Ignore temporary relations in RelidByRelfilenumber() Temporary relations may share the same RelFileNumber with a permanent relation, or other temporary relations associated with other sessions. Being able to uniquely identify a temporary relation would require RelidByRelfilenumber() to know about the proc number of the temporary relation it wants to identify, something it is not designed for since its introduction in `f01d1ae3a1`. There are currently three callers of RelidByRelfilenumber(): - autoprewarm. - Logical decoding, reorder buffer. - pg_filenode_relation(), that attempts to find a relation OID based on a tablespace OID and a RelFileNumber. This makes the situation problematic particularly for the first two cases, leading to the possibility of random ERRORs due to inconsistencies that temporary relations can create in the cache maintained by RelidByRelfilenumber(). The third case should be less of an issue, as I suspect that there are few direct callers of pg_filenode_relation(). The window where the ERRORs are happen is very narrow, requiring an OID wraparound to create a lookup conflict in RelidByRelfilenumber() with a temporary table reusing the same OID as another relation already cached. The problem is easier to reach in workloads with a high OID consumption rate, especially with a higher number of temporary relations created. We could get pg_filenode_relation() and RelidByRelfilenumber() to work with temporary relations if provided the means to identify them with an optional proc number given in input, but the years have also shown that we do not have a use case for it, yet. Note that this could not be backpatched if pg_filenode_relation() needs changes. It is simpler to ignore temporary relations. Reported-by: Shenhao Wang <wangsh.fnst@fujitsu.com> Author: Vignesh C <vignesh21@gmail.com> Reviewed-By: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> Reviewed-By: Robert Haas <robertmhaas@gmail.com> Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Reviewed-By: Takamichi Osumi <osumi.takamichi@fujitsu.com> Reviewed-By: Michael Paquier <michael@paquier.xyz> Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com> Reported-By: Shenhao Wang <wangsh.fnst@fujitsu.com> Discussion: https://postgr.es/m/bbaaf9f9-ebb2-645f-54bb-34d6efc7ac42@fujitsu.com Backpatch-through: 13		3 weeks ago
config	Don't put library-supplied -L/-I switches before user-supplied ones.	1 month ago
contrib	Add CHECK_FOR_INTERRUPTS in contrib/pg_buffercache functions.	3 weeks ago
doc	Ignore temporary relations in RelidByRelfilenumber()	3 weeks ago
src	Ignore temporary relations in RelidByRelfilenumber()	3 weeks ago
.cirrus.star	ci: Simplify ci-os-only handling	4 weeks ago
.cirrus.tasks.yml	ci: Simplify ci-os-only handling	4 weeks ago
.cirrus.yml	ci: Per-repo configuration for manually trigger tasks	4 weeks ago
.dir-locals.el	Make Emacs perl-mode indent more like perltidy.	7 years ago
.editorconfig	Add .editorconfig	6 years ago
.git-blame-ignore-revs	Add commit `7229ebe011` to .git-blame-ignore-revs.	1 year ago
.gitattributes	Fix git whitespace warning	4 weeks ago
.gitignore	Update top-level .gitignore.	3 years ago
COPYRIGHT	Align organization wording in copyright statement	4 months ago
GNUmakefile.in	Allow selecting the git revision to be packaged by "make dist".	1 year ago
HISTORY	Canonicalize some URLs	6 years ago
Makefile	Adapt REL_17_STABLE to its new status as a stable branch	1 year ago
README.md	Adapt REL_17_STABLE to its new status as a stable branch	1 year ago
aclocal.m4	autoconf: Move export_dynamic determination to configure	3 years ago
configure	Stamp 17.6.	1 month ago
configure.ac	Stamp 17.6.	1 month ago
meson.build	Stamp 17.6.	1 month ago
meson_options.txt	Allow selecting the git revision to be packaged by "make dist".	1 year ago

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.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/17/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/17/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/.