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1. Make sure that we don't decrement SxactGlobalXminCount twice when the SXACT_FLAG_RO_SAFE optimization is reached in a parallel query. This could trigger a sanity check failure in assert builds. Non-assert builds recompute the count in SetNewSxactGlobalXmin(), so the problem was hidden, explaining the lack of field reports. Add a new isolation test to exercise that case. 2. Remove an assertion that the DOOMED flag can't be set on a partially released SERIALIZABLEXACT. Instead, ignore the flag (our transaction was already determined to be read-only safe, and DOOMED is in fact set during partial release, and there was already an assertion that it wasn't set sooner). Improve an existing isolation test so that it reaches that case (previously it wasn't quite testing what it was supposed to be testing; see discussion). Back-patch to 12. Bug #17116. Defects in commit 47a338cf. Reported-by: Alexander Lakhin <exclusion@gmail.com> Discussion: https://postgr.es/m/17116-d6ca217acc180e30%40postgresql.org
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/.