[Dovecot] Quota/Dict Postgres Trigger

I posted the trigger for v1.1 versions of Dovecot on the Wiki (http://wiki.dovecot.org/Quota/Dict ) and while I understand the comment posted about two process
inserting at the same time, I'm not sure I understand how this is
fixed in v1.2 other than via the revised trigger in the Wiki. Does
someone have a known working trigger that will handle a double insert
correctly?

Also, out of curiosity why wasn't the code for dict written to do an
update first and then an insert if this failed? That would eliminate
the need for this trigger.

Thanks.

-Warren