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Add additional heuristics to the algorithm for locating an optimal split location. New logic identifies localized monotonically increasing values in indexes with multiple columns. When this insertion pattern is detected, page splits split just after the new item that provoked a page split (or apply leaf fillfactor in the style of a rightmost page split). This optimization is a variation of the long established leaf fillfactor optimization used during rightmost page splits. 50/50 page splits are only appropriate with a pattern of truly random insertions, where the average space utilization ends up at 65% - 70%. Without this patch, affected cases have leaf pages that are no more than about 50% full on average. Future insertions can never make use of the free space left behind. With this patch, affected cases have leaf pages that are about 90% full on average (assuming a fillfactor of 90). Localized monotonically increasing insertion patterns are presumed to be fairly common in real-world applications. There is a fair amount of anecdotal evidence for this. Both pg_depend system catalog indexes (pg_depend_depender_index and pg_depend_reference_index) are at least 20% smaller after the regression tests are run when the optimization is available. Furthermore, many of the indexes created by a fair use implementation of TPC-C for Postgres are consistently about 40% smaller when the optimization is available. Note that even pg_upgrade'd v3 indexes make use of this optimization. Author: Peter Geoghegan Reviewed-By: Heikki Linnakangas Discussion: https://postgr.es/m/CAH2-WzkpKeZJrXvR_p7VSY1b-s85E3gHyTbZQzR0BkJ5LrWF_A@mail.gmail.com
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: https://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. 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 https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.