Rafal Pietrak wrote:
On Thu, 2006-05-25 at 10:33 +0200, Thomas Hallgren wrote:
Rafal Pietrak wrote:
I'd like to propose a 'syntax/semantics' of such trigger:
Triggers normally execute inside of a transaction.
A COMMIT within a trigger could mean: "do a fork: fork-1) return to the
main and schedule COMMIT there, fork-2) continue in bacground".
And what if fork-1) returns to the main, attempts the COMMIT but instead and rolls back due
to a violated constraint? Where does that leave fork-2?
Regards,
Thomas Hallgren
No problem at all (at least in particular case of an application I have
in mind :). The precedure that remains within fork-2 just does a time
consuming housekeeping. Like a cleanup - always succeeds, even if
sometimes is not really necesary (like in case of main rolling-back).
A somewhat limited use-case to form generic database functionality on, wouldn't you say?
And that's exacly why I thing that it should be 'released to run' by
RDBMS *after* the main COMMITS (or ROLLES-BACK). It should be run on
COMMITED (visible to the world) changes, not on session trancients.
Right, so it's not a trigger. It's another session (another transaction) that reacts on a
notification that is sent only if the first transaction succeeds. This is exactly what
notify/listen is for.
Regards,
Thomas Hallgren
