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index.c supposed that it could just use a PG_TRY block to clean up the state associated with an active REINDEX operation. However, that code doesn't run if we do a FATAL exit --- for example, due to a SIGTERM shutdown signal --- while the REINDEX is happening. And that state does get consulted during catalog accesses, which makes it problematic if we do any catalog accesses during shutdown --- for example, to clean up any temp tables created in the session. If this combination of circumstances occurred, we could find ourselves trying to access already-freed memory. In debug builds that'd fairly reliably cause an assertion failure. In production we might often get away with it, but with some bad luck it could cause a core dump. Another possible bad outcome is an erroneous conclusion that an index-to-be-accessed is being reindexed; but it looks like that would be unlikely to have any consequences worse than failing to drop temp tables right away. (They'd still get dropped by the next session that uses that temp schema.) To fix, get rid of the use of PG_TRY here, and instead hook into the transaction abort mechanisms to clean up reindex state. Per bug #16378 from Alexander Lakhin. This has been wrong for a very long time, so back-patch to all supported branches. Discussion: https://postgr.es/m/16378-7a70ca41b3ec2009@postgresql.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/.