Re: Making AFTER triggers act properly in PL functions

Stephan Szabo <sszabo@megazone.bigpanda.com> writes:
> On Wed, 8 Sep 2004, Tom Lane wrote:
>> It wouldn't quite work to use just transaction ID as the marker, since
>> the inner SET CONSTRAINTS is very possibly done without using a
>> subtransaction.  But command ID or query nesting level or some such
>> would work.  I think the main concern here would be the space cost of
>> adding still another field to the trigger records ... is it worth it?

> Would it be possible to basically alias the space for dte_done_xid to hold
> either the xid if it's done or the <whatever> if it's in progress? That's
> ugly, but it would presumably not increase the size of the record.

I found a way to do this, which actually is to forget the done_xid field
altogether and just store the "firing ID" number.  Since firing ID
increases monotonically throughout a transaction, all triggers fired
during a given subtransaction will have IDs >= the subtransaction-start-
time ID counter.  So we can clean up by looking for that, which is much
faster than the TransactionId testing anyway.
        regards, tom lane