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Ever since we split the statistics collector's reports into per-database files (commit 187492b6c2e8cafc), backends have been seeing stale statistics for shared catalogs. This is because the inquiry message only prompts the collector to write the per-database file for the requesting backend's own database. Stats for shared catalogs are in a separate file for "DB 0", which didn't get updated. In normal operation this was partially masked by the fact that the autovacuum launcher would send an inquiry message at least once per autovacuum_naptime that asked for "DB 0"; so the shared-catalog stats would never be more than a minute out of date. However the problem becomes very obvious with autovacuum disabled, as reported by Peter Eisentraut. To fix, redefine the semantics of inquiry messages so that both the specified DB and DB 0 will be dumped. (This might seem a bit inefficient, but we have no good way to know whether a backend's transaction will look at shared-catalog stats, so we have to read both groups of stats whenever we request stats. Sending two inquiry messages would definitely not be better.) Back-patch to 9.3 where the bug was introduced. Report: <56AD41AC.1030509@gmx.net>
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. 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/.