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Tom Lane 0d3b231eeb Further repair of eqjoinsel ndistinct-clamping logic. 
Examination of examples provided by Mark Kirkwood and others has convinced
me that actually commit 7f3eba30c9 was quite
a few bricks shy of a load.  The useful part of that patch was clamping
ndistinct for the inner side of a semi or anti join, and the reason why
that's needed is that it's the only way that restriction clauses
eliminating rows from the inner relation can affect the estimated size of
the join result.  I had not clearly understood why the clamping was
appropriate, and so mis-extrapolated to conclude that we should clamp
ndistinct for the outer side too, as well as for both sides of regular
joins.  These latter actions were all wrong, and are reverted with this
patch.  In addition, the clamping logic is now made to affect the behavior
of both paths in eqjoinsel_semi, with or without MCV lists to compare.
When we have MCVs, we suppose that the most common values are the ones
that are most likely to survive the decimation resulting from a lower
restriction clause, so we think of the clamping as eliminating non-MCV
values, or potentially even the least-common MCVs for the inner relation.

Back-patch to 8.4, same as previous fixes in this area.
2011-09-01 00:19:38 -04:00
config Improve detection of Python 3.2 installations 2011-08-18 14:43:16 +03:00
contrib Fix not-backwards-compatible pg_upgrade test for prepared transactions. 2011-08-30 17:15:00 -04:00
doc The replication status values in pg_stat_replication was changed to 2011-08-31 12:37:37 +03:00
src Further repair of eqjoinsel ndistinct-clamping logic. 2011-09-01 00:19:38 -04:00
.gitignore Add gitignore for mingw/cygwin build outputs 2011-06-09 18:11:47 +02:00
aclocal.m4
configure Include $cc_string in the info reported by a configure run. 2011-08-28 17:14:52 -04:00
configure.in Include $cc_string in the info reported by a configure run. 2011-08-28 17:14:52 -04:00
COPYRIGHT Stamp copyrights for year 2011. 2011-01-01 13:18:15 -05:00
GNUmakefile.in Build src/ before contrib/ in make world 2011-08-24 21:34:49 +03:00
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

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/.