1c7675a7a4
When ComputeXidHorizons() was called before MyDatabaseOid is set, e.g. because a dead row in a shared relation is encountered during InitPostgres(), the horizon for normal tables was computed too aggressively, ignoring all backends connected to a database. During subsequent pruning in a data table the too aggressive horizon could end up still being used, possibly leading to still needed tuples being removed. Not good. This is a bug in dc7420c2c92, which the test added in 94bc27b5768 made visible, if run with force_parallel_mode set to regress. In that case the bug is reliably triggered, because "pruning_query" is run in a parallel worker and the start of that parallel worker is likely to encounter a dead row in pg_database. The fix is trivial: Compute a more pessimistic data table horizon if MyDatabaseId is not yet known. Author: Andres Freund Discussion: https://postgr.es/m/20201029040030.p4osrmaywhqaesd4@alap3.anarazel.de
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/.