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Tom Lane 8f9f198603 Restructure subtransaction handling to reduce resource consumption, as per recent discussions. Invent SubTransactionIds that are managed like CommandIds (ie, counter is reset at start of each top transaction), and use these instead of TransactionIds to keep track of subtransaction status in those modules that need it. This means that a subtransaction does not need an XID unless it actually inserts/modifies rows in the database. Accordingly, don't assign it an XID nor take a lock on the XID until it tries to do that. This saves a lot of overhead for subtransactions that are only used for error recovery (eg plpgsql exceptions). Also, arrange to release a subtransaction's XID lock as soon as the subtransaction exits, in both the commit and abort cases. This avoids holding many unique locks after a long series of subtransactions. The price is some additional overhead in XactLockTableWait, but that seems acceptable. Finally, restructure the state machine in xact.c to have a more orthogonal set of states for subtransactions.		2004-09-16 16:58:44 +00:00
config	Send thread test output to file descriptor 5 like configure does rather	2004-09-11 02:12:17 +00:00
contrib	Fix contrib/cube and contrib/seg to compile on Windows.	2004-09-14 04:21:38 +00:00
doc	Minor doc tweak: mention that function names can be optionally schema-	2004-09-16 04:16:08 +00:00
src	Restructure subtransaction handling to reduce resource consumption,	2004-09-16 16:58:44 +00:00
COPYRIGHT	Update copyright to 2004.	2004-08-29 04:13:13 +00:00
GNUmakefile.in	PostgreSQL extension makefile framework ("pgxs"), by Fabien Coelho, with	2004-07-30 12:26:40 +00:00
Makefile	Restructure the key include files per recent pghackers discussion: there	2001-02-10 02:31:31 +00:00
README	Remove JDBC from the build system and documentation, too.	2004-01-19 21:20:06 +00:00
README.CVS	Some further editorializing on README.CVS.	2004-03-28 06:09:08 +00:00
aclocal.m4	Add new auto-detection of thread flags.	2004-04-23 18:15:55 +00:00
configure	Send thread test output to file descriptor 5 like configure does rather	2004-09-11 02:12:17 +00:00
configure.in	Use $PORTNAME consistently instead of $host_os, where appropriate.	2004-09-10 13:53:40 +00:00

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 several language
bindings, including C and Tcl.

The JDBC, ODBC, C++, and Python interfaces have been moved to the PostgreSQL
Projects Web Site at http://gborg.postgresql.org for separate maintenance.
A Perl DBI/DBD driver is available from CPAN.

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
ftp://ftp.postgresql.org/pub/.  For more information look at our web
site located at http://www.postgresql.org/.