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Tom Lane 6cb86143e8 Allow aggregates to provide estimates of their transition state data size. Formerly the planner had a hard-wired rule of thumb for guessing the amount of space consumed by an aggregate function's transition state data. This estimate is critical to deciding whether it's OK to use hash aggregation, and in many situations the built-in estimate isn't very good. This patch adds a column to pg_aggregate wherein a per-aggregate estimate can be provided, overriding the planner's default, and infrastructure for setting the column via CREATE AGGREGATE. It may be that additional smarts will be required in future, perhaps even a per-aggregate estimation function. But this is already a step forward. This is extracted from a larger patch to improve the performance of numeric and int8 aggregates. I (tgl) thought it was worth reviewing and committing this infrastructure separately. In this commit, all built-in aggregates are given aggtransspace = 0, so no behavior should change. Hadi Moshayedi, reviewed by Pavel Stehule and Tomas Vondra		2013-11-16 16:03:40 -05:00
config	Remove maintainer-check target, fold into normal build	2013-10-10 20:11:56 -04:00
contrib	pg_upgrade: Fix some whitespace oddities	2013-11-16 11:35:44 -05:00
doc	Allow aggregates to provide estimates of their transition state data size.	2013-11-16 16:03:40 -05:00
src	Allow aggregates to provide estimates of their transition state data size.	2013-11-16 16:03:40 -05:00
.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/.