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Alvaro Herrera 1df0122daa Truncate pg_multixact/'s contents during crash recovery Commit `9dc842f08` of 8.2 era prevented MultiXact truncation during crash recovery, because there was no guarantee that enough state had been setup, and because it wasn't deemed to be a good idea to remove data during crash recovery anyway. Since then, due to Hot-Standby, streaming replication and PITR, the amount of time a cluster can spend doing crash recovery has increased significantly, to the point that a cluster may even never come out of it. This has made not truncating the content of pg_multixact/ not defensible anymore. To fix, take care to setup enough state for multixact truncation before crash recovery starts (easy since checkpoints contain the required information), and move the current end-of-recovery actions to a new TrimMultiXact() function, analogous to TrimCLOG(). At some later point, this should probably done similarly to the way clog.c is doing it, which is to just WAL log truncations, but we can't do that for the back branches. Back-patch to 9.0. 8.4 also has the problem, but since there's no hot standby there, it's much less pressing. In 9.2 and earlier, this patch is simpler than in newer branches, because multixact access during recovery isn't required. Add appropriate checks to make sure that's not happening. Andres Freund		2013-11-29 21:47:15 -03:00
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	doc: Enhance documentation of ssl_ciphers setting a bit	2013-11-29 09:06:28 -05:00
src	Truncate pg_multixact/'s contents during crash recovery	2013-11-29 21:47:15 -03:00
.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
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
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

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:

	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/.