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until Bind is received, so that actual parameter values are visible to the planner. Make use of the parameter values for estimation purposes (but don't fold them into the actual plan). This buys back most of the potential loss of plan quality that ensues from using out-of-line parameters instead of putting literal values right into the query text. This patch creates a notion of constant-folding expressions 'for estimation purposes only', in which case we can be more aggressive than the normal eval_const_expressions() logic can be. Right now the only difference in behavior is inserting bound values for Params, but it will be interesting to look at other possibilities. One that we've seen come up repeatedly is reducing now() and related functions to current values, so that queries like ... WHERE timestampcol > now() - '1 day' have some chance of being planned effectively. Oliver Jowett, with some kibitzing from Tom Lane.
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/.