8cfbdf8f4d
check_foreign_key incorrectly used a single cache entry for its saved plans for a 'c' (cascade) trigger, although there are two different queries to execute depending on whether it fires for an update or a delete. This caused the wrong things to be done if both types of event occur in one session. (This was indeed visible in the triggers regression test, but apparently nobody ever questioned it.) To fix, add the operation type to the cache key. Its debug log output failed to distinguish update from delete events, too. Also, change the intended trigger usage from BEFORE ROW to AFTER ROW, and add checks insisting on that usage. BEFORE is really rather unsafe, since if there are other BEFORE triggers they might change or cancel the operation we are trying to check. AFTER triggers are the standard way to propagate changes to other rows, so we should follow that way here. In passing, remove a useless duplicate lookup of the cache entry. This code is mostly intended as a documentation example, so we won't consider a back-patch. Author: Dmitrii Bondar <d.bondar@postgrespro.ru> Reviewed-by: Paul Jungwirth <pj@illuminatedcomputing.com> Reviewed-by: Lilian Ontowhee <ontowhee@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/79755a2b18ed4fe5e29da6a87a1e00d1@postgrespro.ru
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.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.