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Amit Kapila d3ceb20846 Prevent invalidation of newly created replication slots.
A race condition could cause a newly created replication slot to become
invalidated between WAL reservation and a checkpoint.

Previously, if the required WAL was removed, we retried the reservation
process. However, the slot could still be invalidated before the retry if
the WAL was not yet removed but the checkpoint advanced the redo pointer
beyond the slot's intended restart LSN and computed the minimum LSN that
needs to be preserved for the slots.

The fix is to acquire an exclusive lock on ReplicationSlotAllocationLock
during WAL reservation to serialize WAL reservation and checkpoint's
minimum restart_lsn computation. This ensures that, if WAL reservation
occurs first, the checkpoint waits until restart_lsn is updated before
removing WAL. If the checkpoint runs first, subsequent WAL reservations
pick a position at or after the latest checkpoint's redo pointer.

We can't use the same fix for branch 17 and prior because commit
2090edc6f3 changed to compute to the minimum restart_LSN among slot's at
the beginning of checkpoint (or restart point). The fix for 17 and prior
branches is under discussion and will be committed separately.

Reported-by: suyu.cmj <mengjuan.cmj@alibaba-inc.com>
Author: Hou Zhijie <houzj.fnst@fujitsu.com>
Reviewed-by: Vitaly Davydov <v.davydov@postgrespro.ru>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Backpatch-through: 18
Discussion: https://postgr.es/m/5e045179-236f-4f8f-84f1-0f2566ba784c.mengjuan.cmj@alibaba-inc.com
2025-12-08 05:33:14 +00:00
.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 amcheck: Fix snapshot usage in bt_index_parent_check 2025-12-04 18:12:08 +01:00
doc amcheck: Fix snapshot usage in bt_index_parent_check 2025-12-04 18:12:08 +01:00
src Prevent invalidation of newly created replication slots. 2025-12-08 05:33:14 +00:00
.abi-compliance-history Update .abi-compliance-history for change to CreateStatistics(). 2025-11-17 14:14:41 -06:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:09:53 -04:00
.cirrus.tasks.yml ci: Improve OpenBSD core dump backtrace handling. 2025-11-06 17:49:22 +13:00
.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 previous commit to .git-blame-ignore-revs. 2025-10-21 10:02:19 -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 18.1. 2025-11-10 16:52:06 -05:00
configure.ac Stamp 18.1. 2025-11-10 16:52:06 -05:00
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 Add check for large files in meson.build 2025-11-12 09:02:29 +09:00
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

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/.