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Heikki Linnakangas 82b43f7df2 Don't update relfrozenxid if any pages were skipped.
Vacuum recognizes that it can update relfrozenxid by checking whether it has
processed all pages of a relation. Unfortunately it performed that check
after truncating the dead pages at the end of the relation, and used the new
number of pages to decide whether all pages have been scanned. If the new
number of pages happened to be smaller or equal to the number of pages
scanned, it incorrectly decided that all pages were scanned.

This can lead to relfrozenxid being updated, even though some pages were
skipped that still contain old XIDs. That can lead to data loss due to xid
wraparounds with some rows suddenly missing. This likely has escaped notice
so far because it takes a large number (~2^31) of xids being used to see the
effect, while a full-table vacuum before that would fix the issue.

The incorrect logic was introduced by commit
b4b6923e03. Backpatch this fix down to 8.4,
like that commit.

Andres Freund, with some modifications by me.
2013-11-27 13:43:27 +02:00
config Remove maintainer-check target, fold into normal build 2013-10-10 20:11:56 -04:00
contrib Defend against bad trigger definitions in contrib/lo's lo_manage() trigger. 2013-11-23 22:46:43 -05:00
doc Documentation fix for ecpg. 2013-11-27 11:03:59 +01:00
src Don't update relfrozenxid if any pages were skipped. 2013-11-27 13:43:27 +02:00
.dir-locals.el Update Emacs configuration 2013-08-13 20:08:44 -04:00
.gitattributes gitattributes: Make syntax compatible with older Git versions 2013-11-12 21:58:46 -05:00
.gitignore Add *.pot to .gitignore 2013-10-19 10:56:52 -04:00
aclocal.m4 Remove cvs keywords from all files. 2010-09-20 22:08:53 +02:00
configure Get rid of use of asprintf() in favor of a more portable implementation. 2013-10-22 18:42:13 -04:00
configure.in Fix whitespace issues found by git diff --check, add gitattributes 2013-11-10 14:48:29 -05:00
COPYRIGHT Update copyrights for 2013 2013-01-01 17:15:01 -05:00
GNUmakefile.in Remove maintainer-check target, fold into normal build 2013-10-10 20:11:56 -04:00
Makefile Allow make check in PL directories 2011-02-15 06:52:12 +02:00
README Remove useless whitespace at end of lines 2010-11-23 22:34:55 +02:00
README.git Fix doc links in README file to work with new website layout 2013-11-12 12:53:32 +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:

	http://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.  Changes between all PostgreSQL releases are recorded in the
file HISTORY.  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
http://www.postgresql.org/download/.  For more information look at our
web site located at http://www.postgresql.org/.