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Melanie Plageman c2a23dcf9e Use the newest to-be-frozen xid as the conflict horizon for freezing
Previously WAL records that froze tuples used OldestXmin as the snapshot
conflict horizon, or the visibility cutoff if the page would become
all-frozen. Both are newer than (or equal to) the newst XID actually
frozen on the page.

Track the newest XID that will be frozen and use that as the snapshot
conflict horizon instead. This yields an older horizon resulting in
fewer query cancellations on standbys.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/CAAKRu_bbaUV8OUjAfVa_iALgKnTSfB4gO3jnkfpcFgrxEpSGJQ%40mail.gmail.com
2026-03-10 15:24:39 -04:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Portable StaticAssertExpr 2026-03-06 09:27:54 +01:00
contrib CREATE SUBSCRIPTION ... SERVER. 2026-03-06 08:27:56 -08:00
doc Introduce the REPACK command 2026-03-10 19:56:39 +01:00
src Use the newest to-be-frozen xid as the conflict horizon for freezing 2026-03-10 15:24:39 -04:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:09:34 -04:00
.cirrus.tasks.yml Revert "Change default value of default_toast_compression to "lz4"" 2026-03-05 08:25:35 +09:00
.cirrus.yml ci: Per-repo configuration for manually trigger tasks 2025-08-14 11:54:03 -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
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.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 Move comment back to better place 2026-03-09 10:36:16 +01:00
configure.ac Move comment back to better place 2026-03-09 10:36:16 +01:00
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 Portable StaticAssertExpr 2026-03-06 09:27:54 +01:00
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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/.