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When ExecBRUpdateTriggers()'s GetTupleForTrigger() follows an EPQ chain the former needs to run the result tuple through the junkfilter again, and update the slot containing the new version of the tuple to contain that new version. The input tuple may already be in the junkfilter's output slot, which used to be OK - we don't need the previous version anymore. Unfortunately ff11e7f4b9ae started to use ExecCopySlot() to update newslot, and ExecCopySlot() doesn't support copying a slot into itself, leading to a slot in a corrupt state, which then can cause crashes or other symptoms. Fix this by skipping the ExecCopySlot() when copying into itself. While we could have easily made ExecCopySlot() handle that case, it seems better to add an assert forbidding doing so instead. As the goal of copying might be to make the contents of one slot independent from another, it seems failure prone to handle doing so silently. A follow-up commit will add tests for the obviously under-covered combination of EPQ and triggers. Done as a separate commit as it might make sense to backpatch them further than this bug. Also remove confusion with confusing variable names for slots in ExecBRDeleteTriggers() and ExecBRUpdateTriggers(). Bug: #16036 Reported-By: Антон Власов Author: Andres Freund Discussion: https://postgr.es/m/16036-28184c90d952fb7f@postgresql.org Backpatch: 12-, where ff11e7f4b9ae was merged
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/.