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This patch merges the responsibility for NOT-flattening into eval_const_expressions' processing. It wasn't done that way originally because prepqual.c is far older than eval_const_expressions. But putting this work into eval_const_expressions saves one pass over the qual trees, and in fact saves even more than that because we can exploit the knowledge that the subexpressions have already been recursively simplified. Doing it this way also lets us do it uniformly over all expressions, whereas prepqual.c formerly just did it at top level to save cycles. That should improve the planner's ability to recognize logically-equivalent constructs. While at it, also add the ability to fold a NOT into BooleanTest and NullTest constructs (the latter only for the scalar-datatype case). Per discussion of bug #5702. |
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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/.