upstream/postgresql
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2026-04-08 18:51:56 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions
Base de données relationnelle
61790 commits 38 branches 679 tags 836 MiB
C 84.5%
PLpgSQL 6.1%
Perl 4.9%
Yacc 1.2%
Meson 0.7%
Other 2.4%
Find a file
Tom Lane 3aee628370 Fix "variable not found in subplan target lists" in semijoin de-duplication. 
One mechanism we have for implementing semi-joins is to de-duplicate
the output of the RHS and then treat the join as a plain inner join.
Initial construction of the join's SpecialJoinInfo identifies the
RHS columns that need to be de-duplicated, but later we may find that
some of those don't need to be handled explicitly, either because
they're known to be constant or because they are redundant with some
previous column.

Up to now, while sort-based de-duplication handled such cases well,
hash-based de-duplication didn't: we'd still hash on all of the
originally-identified columns.  This is probably not a very big
deal performance-wise, but in the wake of commit a3179ab69 it can
cause planner errors.  That happens when join elimination causes
recalculation of variables' attr_needed bitmapsets, and we decide
that a variable mentioned in a semijoin clause doesn't need to be
propagated up to the join level anymore.

There are a number of ways we could slice the blame for this, but the
only fix that doesn't result in pessimizing plans for loosely-related
cases is to be more careful about not hashing columns we don't
actually need to de-duplicate.  We can install that consideration
into create_unique_paths in master, or the predecessor code in
create_unique_path in v18, without much refactoring.

(As follow-up work, it might be a good idea to look at more-invasive
refactoring, in hopes of preventing other bugs in this area.  But
with v18 release so close, there's not time for that now, nor would
we be likely to want to put such refactoring into v18 anyway.)

Reported-by: Sergey Soloviev <sergey.soloviev@tantorlabs.ru>
Diagnosed-by: Richard Guo <guofenglinux@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Richard Guo <guofenglinux@gmail.com>
Discussion: https://postgr.es/m/1fd1a421-4609-4d46-a1af-ab74d5de504a@tantorlabs.ru
Backpatch-through: 18
2025-08-28 13:49:20 -04:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Don't put library-supplied -L/-I switches before user-supplied ones. 2025-07-29 15:17:40 -04:00
contrib Put "excludeOnly" GIN scan keys at the end of the scankey array. 2025-08-26 12:08:57 -04:00
doc Document privileges required for vacuumdb --missing-stats-only. 2025-08-26 14:49:01 -05:00
src Fix "variable not found in subplan target lists" in semijoin de-duplication. 2025-08-28 13:49:20 -04:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:09:53 -04:00
.cirrus.tasks.yml ci: Simplify ci-os-only handling 2025-08-14 12:09:53 -04:00
.cirrus.yml ci: Per-repo configuration for manually trigger tasks 2025-08-14 11:33:44 -04:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add script to keep .editorconfig in sync with .gitattributes 2025-02-01 10:09:45 +01:00
.git-blame-ignore-revs Add commit 07448b3969 to .git-blame-ignore-revs. 2025-07-01 14:35:59 -05:00
.gitattributes Fix git whitespace warning 2025-08-15 10:32:22 +02:00
.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 Stamp 18beta3. 2025-08-11 17:02:23 -04:00
configure.ac Stamp 18beta3. 2025-08-11 17:02:23 -04:00
COPYRIGHT Align organization wording in copyright statement 2025-05-16 11:20:07 -04:00
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 Adapt REL_18_STABLE to its new status as a stable branch 2025-06-29 23:00:00 -04:00
meson.build oauth: Explicitly depend on -pthread 2025-08-26 14:28:05 -07:00
meson_options.txt Add support for basic NUMA awareness 2025-04-07 23:08:17 +02:00
README.md Adapt REL_18_STABLE to its new status as a stable branch 2025-06-29 23:00:00 -04:00

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/18/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/18/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/.