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We shouldn't ever need to rely on whether HEAP_XMAX_INVALID is set in t_infomask when considering whether or not an xmax should be deemed already frozen, since that status flag is just a hint. The only acceptable representation for an "xmax_already_frozen" raw xmax field is the transaction ID value zero (also known as InvalidTransactionId). Adjust code that superficially appeared to rely on HEAP_XMAX_INVALID to make the rule about xmax_already_frozen clear. Also avoid needlessly rereading the tuple's raw xmax. Oversight in bugfix commit d2599ecf. There is no evidence that this ever led to incorrect behavior, so no backpatch. The worst consequence of this bug was that VACUUM could hypothetically fail to notice and report on certain kinds of corruption, which seems fairly benign. Author: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/CAH2-Wzkh3DMCDRPfhZxj9xCq9v3WmzvmbiCpf1dNKUBPadhCbQ@mail.gmail.com
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/.