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When building BRIN indexes, the brinbuildCallback only advances to the next page range when seeing a tuple that doesn't belong to the current one. This means that the index may end up missing ranges at the end of the table, if those pages do not contain any indexable tuples. We tend not to have completely empty pages at the end of a relation, but this also applies to partial indexes, where the tuples may simply not match the index predicate. This results in inefficient scans using the affected BRIN index - without the summaries, the page ranges have to be read and processed, which consumes I/O and possibly also CPU time. The existing code already added empty ranges for earlier parts of the table, this commit makes sure we add them for the ranges at the end of the table too. Patch by Matthias van de Meent, with review/improvements by me. Author: Matthias van de Meent Reviewed-by: Tomas Vondra Discussion: https://postgr.es/m/CAEze2WiMsPZg%3DxkvSF_jt4%3D69k6K7gz5B8V2wY3gCGZ%2B1BzCbQ%40mail.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. 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, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.