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Tom Lane b574fec00f Avoid collation lookup failure when considering a "char" column.
If a "char" column has a statistics histogram, scalarineqsel()
would fail with "cache lookup failed for collation 0".  Avoid
the failing lookup by acting as though the collation is "C".

Prior to commit 06421b084, this code didn't fail because
lc_collate_is_c() intentionally didn't spit up on InvalidOid.
It did act differently though: it would take the non-C-collation
code path and hence apply strxfrm using libc's prevailing locale.
But that seems like the wrong thing for a non-collatable comparison,
so let's not resurrect that aspect.

Author: Feng Wu <wufengwufengwufeng@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CACK3muq6s-O1Wc3w4dRL1Fe8YQ-Fz1zJbezeQwhuLgNxGNEFiA@mail.gmail.com
Backpatch-through: 18
2026-06-28 12:31:29 -04:00
.github ci: Improve ccache handling 2026-06-08 15:26:47 -04:00
config Update config.guess and config.sub 2026-04-09 11:26:14 +02:00
contrib Reject child partition FDWs in FOR PORTION OF 2026-06-27 19:36:51 +02:00
doc Use named boolean parameters for pg_get_*_ddl option arguments 2026-06-28 10:45:26 -04:00
src Avoid collation lookup failure when considering a "char" column. 2026-06-28 12:31:29 -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 previous commit to .git-blame-ignore-revs. 2026-06-04 10:16:21 -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 Stamp 19beta1. 2026-06-01 16:02:13 -04:00
configure.ac Stamp 19beta1. 2026-06-01 16:02:13 -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 Stamp 19beta1. 2026-06-01 16:02:13 -04:00
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

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/.