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Tom Lane 1147035203 Disallow pushing volatile qual expressions down into DISTINCT subqueries. 
A WHERE clause applied to the output of a subquery with DISTINCT should
theoretically be applied only once per distinct row; but if we push it
into the subquery then it will be evaluated at each row before duplicate
elimination occurs.  If the qual is volatile this can give rise to
observably wrong results, so don't do that.

While at it, refactor a little bit to allow subquery_is_pushdown_safe
to report more than one kind of restrictive condition without indefinitely
expanding its argument list.

Although this is a bug fix, it seems unwise to back-patch it into released
branches, since it might de-optimize plans for queries that aren't giving
any trouble in practice.  So apply to 9.4 but not further back.
2014-06-27 11:08:48 -07:00
config Silence Bison deprecation warnings 2014-06-03 22:36:35 -04:00
contrib pg_upgrade: remove pg_multixact files left by initdb 2014-06-24 16:11:06 -04:00
doc Get rid of bogus separate pg_proc entries for json_extract_path operators. 2014-06-26 16:22:15 -07:00
src Disallow pushing volatile qual expressions down into DISTINCT subqueries. 2014-06-27 11:08:48 -07:00
.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 Add mkdtemp() to libpgport. 2014-06-14 09:41:13 -04:00
configure.in Add mkdtemp() to libpgport. 2014-06-14 09:41:13 -04:00
COPYRIGHT Update copyright for 2014 2014-01-07 16:05:30 -05:00
GNUmakefile.in Add TAP tests for client programs 2014-04-14 21:33:46 -04:00
HISTORY Improve text of stub HISTORY file. 2014-02-12 18:16:17 -05:00
Makefile Allow make check in PL directories 2011-02-15 06:52:12 +02:00
README Don't generate plain-text HISTORY and src/test/regress/README anymore. 2014-02-10 20:48:04 -05:00
README.git Don't generate plain-text HISTORY and src/test/regress/README anymore. 2014-02-10 20:48:04 -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.  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/.