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Tom Lane 80a5cf643a Improve contrib/pg_trgm's heuristics for regexp index searches.
When extracting trigrams from a regular expression for search of a GIN or
GIST trigram index, it's useful to penalize (preferentially discard)
trigrams that contain whitespace, since those are typically far more common
in the index than trigrams not containing whitespace.  Of course, this
should only be a preference not a hard rule, since we might otherwise end
up with no trigrams to search for.  The previous coding tended to produce
fairly inefficient trigram search sets for anchored regexp patterns, as
reported by Erik Rijkers.  This patch penalizes whitespace-containing
trigrams, and also reduces the target number of extracted trigrams, since
experience suggests that the original coding tended to select too many
trigrams to search for.

Alexander Korotkov, reviewed by Tom Lane
2014-04-05 20:48:47 -04:00
config Allow use of "z" flag in our printf calls, and use it where appropriate. 2014-01-23 17:18:33 -05:00
contrib Improve contrib/pg_trgm's heuristics for regexp index searches. 2014-04-05 20:48:47 -04:00
doc Fix non-equivalence of VARIADIC and non-VARIADIC function call formats. 2014-04-03 22:02:24 -04:00
src Block signals earlier during postmaster startup. 2014-04-05 18:16:08 -04:00
.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
configure configure.in: Use dnl in place of # where appropriate 2014-02-22 20:42:39 -05:00
configure.in configure.in: Use dnl in place of # where appropriate 2014-02-22 20:42:39 -05:00
COPYRIGHT Update copyright for 2014 2014-01-07 16:05:30 -05:00
GNUmakefile.in Don't generate plain-text HISTORY and src/test/regress/README anymore. 2014-02-10 20:48:04 -05:00
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

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/.