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Amit Kapila d65485b02b Fix xmin advancement during fast_forward decoding.
During logical decoding, we advance catalog_xmin of logical too early in
fast_forward mode, resulting in required catalog data being removed by
vacuum. This mode is normally used to advance the slot without processing
the changes, but we still can't let the slot's xmin to advance to an
incorrect value.

Commit f49a80c481 fixed a similar issue where the logical slot's
catalog_xmin was getting advanced prematurely during non-fast-forward
mode. During xl_running_xacts processing, instead of directly advancing
the slot's xmin to the oldest running xid in the record, it allowed the
xmin to be held back for snapshots that can be used for
not-yet-replayed transactions, as those might consider older txns as
running too. However, it missed the fact that the same problem can happen
during fast_forward mode decoding, as we won't build a base snapshot in
that mode, and the future call to get_changes from the same slot can miss
seeing the required catalog changes leading to incorrect reslts.

This commit allows building the base snapshot even in fast_forward mode to
prevent the early advancement of xmin.

Reported-by: Amit Kapila <amit.kapila16@gmail.com>
Author: Zhijie Hou <houzj.fnst@fujitsu.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: shveta malik <shveta.malik@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Backpatch-through: 13
Discussion: https://postgr.es/m/CAA4eK1LqWncUOqKijiafe+Ypt1gQAQRjctKLMY953J79xDBgAg@mail.gmail.com
Discussion: https://postgr.es/m/OS0PR01MB57163087F86621D44D9A72BF94BB2@OS0PR01MB5716.jpnprd01.prod.outlook.com
2025-04-28 11:55:00 +05:30
config Log LLVM library version in configure output. 2023-10-22 14:32:31 +13:00
contrib Fix xmin advancement during fast_forward decoding. 2025-04-28 11:55:00 +05:30
doc Doc: reword text explaining the --maintenance-db option 2025-04-22 14:58:09 +12:00
src Fix xmin advancement during fast_forward decoding. 2025-04-28 11:55:00 +05:30
.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 Backpatch addition of .git-blame-ignore-revs 2022-08-05 19:36:24 +02:00
.gitattributes Exclude LLVM files from whitespace checks 2024-11-27 11:10:42 +01:00
.gitignore Add portlock directory to .gitignore 2022-11-26 07:47:16 -05:00
aclocal.m4 Probe $PROVE not $PERL while checking for modules needed by TAP tests. 2021-11-22 12:54:52 -05:00
configure Fix detection and handling of strchrnul() for macOS 15.4. 2025-04-01 16:49:51 -04:00
configure.in Fix detection and handling of strchrnul() for macOS 15.4. 2025-04-01 16:49:51 -04:00
COPYRIGHT Update copyright for 2025 2025-01-01 11:21:54 -05:00
GNUmakefile.in Remove temporary portlock directory during make [dist]clean. 2022-11-26 10:30:58 -05:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Don't unset MAKEFLAGS in non-GNU Makefile. 2019-06-25 09:36:21 +12:00
meson.build Disable clang 16's -Wcast-function-type-strict. 2024-11-08 09:44:01 +10:30
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00

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.

PostgreSQL has many language interfaces, many of which are listed here:

	https://www.postgresql.org/download/

See the file INSTALL for instructions on how to build and install
PostgreSQL.  That file also lists supported operating systems and
hardware platforms and contains information regarding any other
software packages that are required to build or run the PostgreSQL
system.  Copyright and license information can be found in the
file COPYRIGHT.  A comprehensive documentation set is included in this
distribution; it can be read as described in the installation
instructions.

The latest version of this software may be obtained at
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.