3c43595217
AFTER triggers using transition tables crashed if they were fired due to a foreign key ON CASCADE update. This is because ExecEndModifyTable flushes the transition tables, on the assumption that any trigger that could need them was already fired during ExecutorFinish. Normally that's true, because we don't allow transition-table-using triggers to be deferred. However, foreign key CASCADE updates force any triggers on the referencing table to be deferred to the outer query level, by means of the EXEC_FLAG_SKIP_TRIGGERS flag. I don't recall all the details of why it's like that and am pretty loath to redesign it right now. Instead, just teach ExecEndModifyTable to skip destroying the TransitionCaptureState when that flag is set. This will allow the transition table data to survive until end of the current subtransaction. This isn't a terribly satisfactory solution, because (1) we might be leaking the transition tables for much longer than really necessary, and (2) as things stand, an AFTER STATEMENT trigger will fire once per RI updating query, ie once per row updated or deleted in the referenced table. I suspect that is not per SQL spec. But redesigning this is a research project that we're certainly not going to get done for v10. So let's go with this hackish answer for now. In passing, tweak AfterTriggerSaveEvent to not save the transition_capture pointer into the event record for a deferrable trigger. This is not necessary to fix the current bug, but it avoids letting dangling pointers to long-gone transition tables persist in the trigger event queue. That's at least a safety feature. It might also allow merging shared trigger states in more cases than before. I added a regression test that demonstrates the crash on unpatched code, and also exposes the behavior of firing the AFTER STATEMENT triggers once per row update. Per bug #14808 from Philippe Beaudoin. Back-patch to v10. Discussion: https://postgr.es/m/20170909064853.25630.12825@wrigleys.postgresql.org |
||
|---|---|---|
| config | ||
| contrib | ||
| doc | ||
| src | ||
| .dir-locals.el | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| GNUmakefile.in | ||
| HISTORY | ||
| Makefile | ||
| README | ||
| README.git | ||
| aclocal.m4 | ||
| configure | ||
| configure.in | ||
README
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/.