On Thu, Mar 8, 2018 at 6:52 AM, Robert Haas <robertmh...@gmail.com> wrote: >> I removed this code since it was wrong. We might want to add some basic >> checks for existence of volatile functions in the WHEN or SET clauses. But I >> agree, it's no different than regular UPDATEs. So may be not a big deal. > > I just caught up on this thread. I'm definitely glad to see that code > go because, wow, that is all kinds of wrong. I don't see a real need > to add any kind of replacement check, either. Prohibiting volatile > functions here doesn't seem likely to accomplish anything useful. It > seems like the most we'd want to do is mention this the documentation > somehow, and I'm not even sure we really need to do that much.
Thanks in large part to Pavan's excellent work, the situation in nodeModifyTable.c is much clearer than it was a few weeks ago. It's now obvious that MERGE is very similar to UPDATE ... FROM, which doesn't have any restrictions on volatile functions. I don't see any sense in prohibiting volatile functions in either case, because it should be obvious to users that that's just asking for trouble. I can believe that someone would make that mistake, just about, but they'd have to be writing their DML statement on auto-pilot. -- Peter Geoghegan
