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Tom Lane 54889ea64b Correctly identify which EC members are computable at a plan node.
find_computable_ec_member() had the wrong mental model of what
its primary caller prepare_sort_from_pathkeys() would do with
the selected EquivalenceClass member expression.  We will not
compute the EC expression in a plan node atop the one returning
the passed-in targetlist; rather, the EC expression will be
computed as an additional column of that targetlist.  So any
Var or quasi-Var used in the given tlist is also available to the
EC expression.  In simple cases this makes no difference because
the given tlist is just a list of Vars or quasi-Vars --- but if
we are considering an appendrel member produced by flattening
a UNION ALL, the tlist may contain expressions, resulting in
failure to match and a "could not find pathkey item to sort"
error.

To fix, we can flatten both the tlist and the EC members with
pull_var_clause(), and then just check for subset-ness, so
that the code is actually shorter than before.

While this bug is quite old, the present patch only works back to
v13.  We could possibly make it work in v12 by back-patching parts
of 375398244.  On the whole though I don't like the risk/reward
ratio of that idea.  v12's final release is next month, meaning
there would be no chance to correct matters if the patch causes a
regression.  Since this failure has escaped notice for 14 years,
it's likely nobody will hit it in the field with v12.

Per bug #18652 from Alexander Lakhin.

Andrei Lepikhov and Tom Lane

Discussion: https://postgr.es/m/18652-deaa782ebcca85d1@postgresql.org
2024-10-12 14:56:08 -04:00
config jit: Remove {llvm-config,clang}-N configure probes. 2024-05-16 13:58:25 +12:00
contrib Stabilize the test added by commit 022564f60c. 2024-10-08 12:13:28 +05:30
doc doc PG 17 relnotes: clarify pg_upgrade and logical slot preserv. 2024-10-09 23:05:50 -04:00
src Correctly identify which EC members are computable at a plan node. 2024-10-12 14:56:08 -04:00
.cirrus.star Remove duplicate words in docs and code comments. 2023-10-09 09:18:47 +05:30
.cirrus.tasks.yml ci: Pin MacPorts version to 2.9.3. 2024-07-25 14:48:18 +12:00
.cirrus.yml ci: Make compute resources for CI configurable 2023-08-23 15:15:28 -07:00
.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 commit 7229ebe011 to .git-blame-ignore-revs. 2024-09-14 20:17:30 +02:00
.gitattributes Remove non-existing file from .gitattributes 2024-02-16 11:39:09 +01:00
.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 Stamp 17.0. 2024-09-23 16:02:53 -04:00
configure.ac Stamp 17.0. 2024-09-23 16:02:53 -04:00
COPYRIGHT Update copyright for 2024 2024-01-03 20:49:05 -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 Adapt REL_17_STABLE to its new status as a stable branch 2024-07-01 08:05:35 +09:00
meson.build Stamp 17.0. 2024-09-23 16:02:53 -04:00
meson_options.txt Allow selecting the git revision to be packaged by "make dist". 2024-05-03 11:08:50 -04:00
README.md Adapt REL_17_STABLE to its new status as a stable branch 2024-07-01 08:05:35 +09:00

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/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/.