Attached a rebased patch with the suggested "ONLY ON" change.
Regards
Arne
From: Arne Roland <A.Roland@index.de> Sent: Monday, March 29, 2021 9:37:53 AM To: David Steele; Alvaro Herrera Cc: Pg Hackers Subject: Re: Rename of triggers for partitioned tables
David Steele wrote: > Arne, thoughts on Álvaro's comments? > > Marking this patch as Waiting for Author.
Thank you for the reminder. I was to absorbed by other tasks. I should be more present in the upcoming weeks.
> I think you did not register the patch in commitfest, so I did that for > you: https://commitfest.postgresql.org/32/2943/
Thank you! I should have done that.
> As you say, triggers on children don't necessarily have to have the same > name as on parent; this already happens when the trigger is renamed in > the child table but not on parent. In that situation the search on the > child will fail, which will cause the whole thing to fail I think. > > We now have the column pg_trigger.tgparentid, and I think it would be > better (more reliable) to search for the trigger in the child by the > tgparentid column instead, rather than by name.
The last patch already checks tgparentid and errors out if either of those do not match. The reasoning behind that was, that I don't see a clear reasonable way to handle this scenario. If the user choose to rename the child trigger, I am at a loss what to do. I thought to pass it back to the user to solve the situation instead of simply ignoring the users earlier rename. Silently renaming sounded a bit presumptuous to me, even though I don't care that much either way.
Do you think silently renaming is better than yielding an error?
> Also, I think it would be good to have > ALTER TRIGGER .. ON ONLY parent RENAME TO .. > to avoid recursing to children. This seems mostly pointless, but since > we've allowed changing the name of the trigger in children thus far, > then we've implicitly made it supported to have triggers that are named > differently. (And it's not entirely academic, since the trigger name > determines firing order.)
If it would be entirely academic, I wouldn't have noticed the whole thing in the first place.
The on only variant sounds like a good idea to me. Even though hardly worth any efford, it seems simple enough. I will work on that.
> Alternatively to this last point, we could decide to disallow renaming > of triggers on children (i.e. if trigger has tgparentid set, then > renaming is disallowed). I don't have a problem with that, but it would > have to be an explicit decision to take.
I rejected that idea, because I was unsure what to do with migrations. If we would be discussing this a few years back, this would have been likely my vote, but I don't see it happening now.