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Alvaro Herrera 042b584c7f
Revert changes to CONCURRENTLY that "sped up" Xmin advance 
This reverts commit d9d076222f "VACUUM: ignore indexing operations
with CONCURRENTLY".

These changes caused indexes created with the CONCURRENTLY option to
miss heap tuples that were HOT-updated and HOT-pruned during the index
creation.  Before these changes, HOT pruning would have been prevented
by the Xmin of the transaction creating the index, but because this
change was precisely to allow the Xmin to move forward ignoring that
backend, now other backends scanning the table can prune them.  This is
not a problem for VACUUM (which requires a lock that conflicts with a
CREATE INDEX CONCURRENTLY operation), but HOT-prune can definitely
occur.  In other words, Xmin advancement was sped up, but at the cost of
corrupting the resulting index.

Regrettably, this means that the new feature in PG14 that RIC/CIC on
very large tables no longer force VACUUM to retain very old tuples goes
away.  We might try to implement it again in a later release, but for
now the risk of indexes missing tuples is too high and there's no easy
fix.

Backpatch to 14, where this change appeared.

Reported-by: Peter Slavov <pet.slavov@gmail.com>
Diagnosys-by: Andrey Borodin <x4mmm@yandex-team.ru>
Diagnosys-by: Michael Paquier <michael@paquier.xyz>
Diagnosys-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/17485-396609c6925b982d%40postgresql.org
2022-05-31 21:24:59 +02:00
config Suppress warning about stack_base_ptr with late-model GCC. 2022-02-17 22:45:34 -05:00
contrib Make relation-enumerating operations be security-restricted operations. 2022-05-09 08:35:12 -07:00
doc Revert changes to CONCURRENTLY that "sped up" Xmin advance 2022-05-31 21:24:59 +02:00
src Revert changes to CONCURRENTLY that "sped up" Xmin advance 2022-05-31 21:24:59 +02:00
.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 Add list of ignorable pgindent commits for git-blame. 2021-06-22 09:06:32 -07:00
.gitattributes gitattributes: Add new entry to silence whitespace error 2021-06-05 07:57:31 +02:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
aclocal.m4 Probe $PROVE not $PERL while checking for modules needed by TAP tests. 2021-11-22 12:54:52 -05:00
configure configure: don't probe for libldap_r if libldap is 2.5 or newer. 2022-05-10 18:42:02 -04:00
configure.ac configure: don't probe for libldap_r if libldap is 2.5 or newer. 2022-05-10 18:42:02 -04:00
COPYRIGHT Update copyright for 2022 2022-01-07 19:04:56 -05:00
GNUmakefile.in add missing tag from commit b8c4261e5e 2021-07-01 15:47:47 -04:00
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
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

README 

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/.