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Alvaro Herrera 3a11485a52 Don't mark pages all-visible spuriously
Dan Wood diagnosed a long-standing problem that pages containing tuples
that are locked by multixacts containing live lockers may spuriously end
up as candidates for getting their all-visible flag set.  This has the
long-term effect that multixacts remain unfrozen; this may previously
pass undetected, but since commit XYZ it would be reported as
  "ERROR: found multixact 134100944 from before relminmxid 192042633"
because when a later vacuum tries to freeze the page it detects that a
multixact that should have gotten frozen, wasn't.

Dan proposed a (correct) patch that simply sets a variable to its
correct value, after a bogus initialization.  But, per discussion, it
seems better coding to avoid the bogus initializations altogether, since
they could give rise to more bugs later.  Therefore this fix rewrites
the logic a little bit to avoid depending on the bogus initializations.

This bug was part of a family introduced in 9.6 by commit a892234f830e;
later, commit 38e9f90a22 fixed most of them, but this one was
unnoticed.

Authors: Dan Wood, Pavan Deolasee, Álvaro Herrera
Reviewed-by: Masahiko Sawada, Pavan Deolasee, Álvaro Herrera
Discussion: https://postgr.es/m/84EBAC55-F06D-4FBE-A3F3-8BDA093CE3E3@amazon.com
2018-05-04 18:23:30 -03:00
config Extend configure's __int128 test to check for a known gcc bug. 2018-01-18 11:09:44 -05:00
contrib Fix broken extract_actual_join_clauses call in 9.6 postgres_fdw. 2018-04-19 18:29:39 -04:00
doc docs: remove "III" version text from pgAdmin link 2018-04-26 11:10:43 -04:00
src Don't mark pages all-visible spuriously 2018-05-04 18:23:30 -03:00
.dir-locals.el emacs: Set indent-tabs-mode in perl-mode 2015-04-12 23:53:23 -04:00
.gitattributes Fix whitespace and remove obsolete gitattributes entry 2016-03-13 16:03:13 -04:00
.gitignore Add .gitignore entries for AIX-specific intermediate build artifacts. 2015-07-08 20:44:22 -04:00
aclocal.m4 Replace our hacked version of ax_pthread.m4 with latest upstream version. 2015-07-08 20:36:06 +03:00
configure Stamp 9.6.8. 2018-02-26 17:13:40 -05:00
configure.in Fix incorrect description of USE_SLICING_BY_8_CRC32C. 2018-04-04 11:25:26 +03:00
COPYRIGHT Update copyright for 2018 2018-01-02 23:30:12 -05:00
GNUmakefile.in Fix distclean/maintainer-clean targets to remove top-level tmp_install dir. 2015-05-13 18:48:05 -04:00
HISTORY Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
Makefile Fix non-GNU makefiles for AIX make. 2017-11-30 00:57:31 -08:00
README Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
README.git Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -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.

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/.