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Neil Conway c119c5bd49 Change the implementation of hash join to attempt to avoid unnecessary work if either of the join relations are empty. The logic is: (1) if the inner relation's startup cost is less than the outer relation's startup cost and this is not an outer join, read a single tuple from the inner relation via ExecHash() - if NULL, we're done (2) read a single tuple from the outer relation - if NULL, we're done (3) build the hash table on the inner relation - if hash table is empty and this is not an outer join, we're done (4) otherwise, do hash join as usual The implementation uses the new MultiExecProcNode API, per a suggestion from Tom: invoking ExecHash() now produces the first tuple from the Hash node's child node, whereas MultiExecHash() builds the hash table. I had to put in a bit of a kludge to get the row count returned for EXPLAIN ANALYZE to be correct: since ExecHash() is invoked to return a tuple, and then MultiExecHash() is invoked, we would return one too many tuples to EXPLAIN ANALYZE. I hacked around this by just manually detecting this situation and subtracting 1 from the EXPLAIN ANALYZE row count.		2005-06-15 07:27:44 +00:00
config	Clean up printf arg-control test, per Kurt Roeckx.	2005-02-24 01:34:45 +00:00
contrib	Simplify shared-memory lock data structures as per recent discussion:	2005-06-14 22:15:33 +00:00
doc	Minor SGML markup cleanup.	2005-06-15 06:29:25 +00:00
src	Change the implementation of hash join to attempt to avoid unnecessary	2005-06-15 07:27:44 +00:00
COPYRIGHT	Tag appropriate files for rc3	2004-12-31 22:04:05 +00:00
GNUmakefile.in	Remove the contents of the src/corba subdirectory: this has been dead code	2005-05-01 06:15:51 +00:00
Makefile	please find attached an alternate submission which addresses open item	2004-10-06 08:50:02 +00:00
README	Remove more traces of libpgtcl from the source tree. Also, make some	2004-10-01 02:00:44 +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	Allow kerberos name and username case sensitivity to be specified from	2005-06-04 20:42:43 +00:00
configure.in	Allow kerberos name and username case sensitivity to be specified from	2005-06-04 20:42:43 +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 C language bindings.

The JDBC, ODBC, C++, Python, and Tcl 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/.