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Kevin Grittner a7516bbc49 Fix an O(N^2) problem in foreign key references. 
Commit 45ba424f improved foreign key lookups during bulk updates
when the FK value does not change.  When restoring a schema dump
from a database with many (say 100,000) foreign keys, this cache
would grow very big and every ALTER TABLE command was causing an
InvalidateConstraintCacheCallBack(), which uses a sequential hash
table scan.  This could cause a severe performance regression in
restoring a schema dump (including during pg_upgrade).

The patch uses a heuristic method of detecting when the hash table
should be destroyed and recreated.
InvalidateConstraintCacheCallBack() adds the current size of the
hash table to a counter.  When that sum reaches 1,000,000, the hash
table is flushed.  This fixes the regression without noticeable
harm to the bulk update use case.

Jan Wieck
Backpatch to 9.3 where the performance regression was introduced.
2015-09-11 13:20:49 -05:00
config Blacklist xlc 32-bit inlining. 2015-07-29 22:53:40 -04:00
contrib Fix error message wording in previous sslinfo commit 2015-09-08 11:10:20 -03:00
doc Correct description of PageHeaderData layout in documentation 2015-09-11 13:03:06 +09:00
src Fix an O(N^2) problem in foreign key references. 2015-09-11 13:20:49 -05:00
.gitignore Add pkg-config files for libpq and ecpg libraries 2013-03-31 16:58:40 -04:00
aclocal.m4
configure AIX: Test the -qlonglong option before use. 2015-07-17 03:02:03 -04:00
configure.in AIX: Test the -qlonglong option before use. 2015-07-17 03:02:03 -04:00
COPYRIGHT Update copyright for 2015 2015-01-06 11:43:46 -05:00
GNUmakefile.in Don't generate plain-text HISTORY and src/test/regress/README anymore. 2014-02-10 20:48:12 -05:00
HISTORY Improve text of stub HISTORY file. 2014-02-12 18:16:27 -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 20:48:12 -05:00
README.git Don't generate plain-text HISTORY and src/test/regress/README anymore. 2014-02-10 20:48:12 -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/.