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There were two issues in how the extended statistics handled NULL values in opclauses. Firstly, the code was oblivious to the possibility that Const may be NULL (constisnull=true) in which case the constvalue is undefined. We need to treat this as a mismatch, and not call the proc. Secondly, the MCV item itself may contain NULL values too - the code already did check that, and updated the match bitmap accordingly, but failed to ensure we won't call the operator procedure anyway. It did work for AND-clauses, because in that case false in the bitmap stops evaluation of further clauses. But for OR-clauses ir was not easy to get incorrect estimates or even trigger a crash. This fixes both issues by extending the existing check so that it looks at constisnull too, and making sure it skips calling the procedure. Discussion: https://postgr.es/m/8736jdhbhc.fsf%40ansel.ydns.eu
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/.