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When performing ANALYZE on inheritance trees, we collect two samples for each relation - one for the relation alone, and one for the inheritance subtree (relation and its child relations). And then we build statistics on each sample, so for each relation we get two sets of statistics. For regular (per-column) statistics this works fine, because the catalog includes a flag differentiating statistics built from those two samples. But we don't have such flag in the extended statistics catalogs, and we ended up updating the same row twice, triggering this error: ERROR: tuple already updated by self The simplest solution is to disable extended statistics on inheritance trees, which is what this commit is doing. In the future we may need to do something similar to per-column statistics, but that requires adding a flag to the catalog - and that's not backpatchable. Moreover, the current selectivity estimation code only works with individual relations, so building statistics on inheritance trees would be pointless anyway. Author: Tomas Vondra Backpatch-to: 10- Discussion: https://postgr.es/m/20190618231233.GA27470@telsasoft.com Reported-by: Justin Pryzby
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/.