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Tom Lane 72cfc17aef Improve handling of unknown-type literals in UNION/INTERSECT/EXCEPT.
This patch causes unknown-type Consts to be coerced to the resolved output
type of the set operation at parse time.  Formerly such Consts were left
alone until late in the planning stage.  The disadvantage of that approach
is that it disables some optimizations, because the planner sees the set-op
leaf query as having different output column types than the overall set-op.
We saw an example of that in a recent performance gripe from Claudio
Freire.

Fixing such a Const requires scribbling on the leaf query in
transformSetOperationTree, but that should be all right since if the leaf
query's semantics depended on that output column, it would already have
resolved the unknown to something else.

Most of the bulk of this patch is a simple adjustment of
transformSetOperationTree's API so that upper levels can get at the
TargetEntry containing a Const to be replaced: it now returns a list of
TargetEntries, instead of just the bare expressions.
2011-03-15 21:52:10 -04:00
config Better support for thread-support flag detection with clang 2011-02-16 23:15:54 +02:00
contrib Remove unused copy_dir() function from pg_upgrade. 2011-03-15 20:52:35 -04:00
doc Adjust doc wording about the casting exceptions for composite types. 2011-03-15 20:47:31 -04:00
src Improve handling of unknown-type literals in UNION/INTERSECT/EXCEPT. 2011-03-15 21:52:10 -04:00
.gitignore Ignore files built by coverage builds 2011-03-08 22:10:00 +02:00
COPYRIGHT Stamp copyrights for year 2011. 2011-01-01 13:18:15 -05:00
GNUmakefile.in Allow make check in PL directories 2011-02-15 06:52:12 +02:00
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 Trivial typo fix. 2010-09-21 14:16:00 -04:00
aclocal.m4 Remove cvs keywords from all files. 2010-09-20 22:08:53 +02:00
configure Support for DragonFly BSD 2011-03-02 21:15:28 +02:00
configure.in Support for DragonFly BSD 2011-03-02 21:15:28 +02:00

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/.