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Robert Haas 7ab9b2f3b7 Rearrange lazy_scan_heap to avoid visibility map race conditions.
We must set the visibility map bit before releasing our exclusive lock
on the heap page; otherwise, someone might clear the heap page bit
before we set the visibility map bit, leading to a situation where the
visibility map thinks the page is all-visible but it's really not.

This problem has existed since 8.4, but it wasn't critical before we
had index-only scans, since the worst case scenario was that the page
wouldn't get vacuumed until the next scan_all vacuum.

Along the way, a couple of minor, related improvements: (1) if we
pause the heap scan to do an index vac cycle, release any visibility
map page we're holding, since really long-running pins are not good
for a variety of reasons; and (2) warn if we see a page that's marked
all-visible in the visibility map but not on the page level, since
that should never happen any more (it was allowed in previous
releases, but not in 9.2).
2012-04-23 22:08:06 -04:00
config Fix configure's search for collateindex.pl. 2012-03-22 00:46:03 -04:00
contrib Fix some typos 2012-04-22 19:23:47 +03:00
doc Minor improvements for CHECK NO INHERIT documentation. 2012-04-23 21:59:17 -04:00
src Rearrange lazy_scan_heap to avoid visibility map race conditions. 2012-04-23 22:08:06 -04:00
.gitignore Add gitignore for mingw/cygwin build outputs 2011-06-09 18:11:47 +02:00
COPYRIGHT Update copyright notices for year 2012. 2012-01-01 18:01:58 -05:00
GNUmakefile.in Add isolation test to check-world and installcheck-world 2012-03-05 20:19:20 +02:00
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 Trivial typo fix. 2010-09-21 14:16:00 -04:00
aclocal.m4 Remove cvs keywords from all files. 2010-09-20 22:08:53 +02:00
configure Fix configure's search for collateindex.pl. 2012-03-22 00:46:03 -04:00
configure.in Allow MinGW builds to use standardly-named OpenSSL libraries. 2012-02-23 15:05:08 -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/.