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Tomas Vondra 943e881733 Do not lock in BufferGetLSNAtomic() on archs with 8 byte atomic reads
On platforms where we can read or write the whole LSN atomically, we do
not need to lock the buffer header to prevent torn LSNs. We can do this
only on platforms with PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY, and when the
pd_lsn field is properly aligned.

For historical reasons the PageXLogRecPtr was defined as a struct with
two uint32 fields. This replaces it with a single uint64 value, to make
the intent clearer. To prevent issues with weak typedefs the value is
still wrapped in a struct.

This also adjusts heapfuncs() in pageinspect, to ensure proper alignment
when reading the LSN from a page on alignment-sensitive hardware.

Idea by Andres Freund. Initial patch by Andreas Karlsson, improved by
Peter Geoghegan. Minor tweaks by me.

Author: Andreas Karlsson <andreas@proxel.se>
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Discussion: https://postgr.es/m/b6610c3b-3f59-465a-bdbb-8e9259f0abc4@proxel.se
2026-03-11 19:46:08 +01:00
.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 Do not lock in BufferGetLSNAtomic() on archs with 8 byte atomic reads 2026-03-11 19:46:08 +01:00
doc Introduce the REPACK command 2026-03-10 19:56:39 +01:00
src Do not lock in BufferGetLSNAtomic() on archs with 8 byte atomic reads 2026-03-11 19:46:08 +01:00
.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
.git-blame-ignore-revs Add commit 7b24959434 to .git-blame-ignore-revs. 2026-03-02 13:23:28 -06:00
.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 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
meson_options.txt Update copyright for 2026 2026-01-01 13:24:10 -05:00
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/.