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In the original implementation, a range-contained-by search had to scan the entire index because an empty range could be lurking anywhere. Improve that by adding a flag to upper GiST entries that says whether the represented subtree contains any empty ranges. Also, make a simple mod to the penalty function to discourage empty ranges from getting pushed into subtrees without any. This needs more work, and the picksplit function should be taught about it too, but that code can be improved without causing an on-disk compatibility break; so we'll leave it for another day. Since we're breaking on-disk compatibility of range values anyway, I took the opportunity to reorganize the range flags bits; the unused RANGE_xB_NULL bits are now adjacent, which might open the door for using them in some other way later. In passing, remove the GiST range opclass entry for <>, which doesn't seem like it can really be indexed usefully. Alexander Korotkov, with some editorializing by Tom
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/.