Hello,
the compatibility section of the "create trigger" page
(http://www.postgresql.org/docs/devel/static/sql-createtrigger.html)
claims that a missing functionality is the ability to define aliases for
the "old" and "new" rows or tables. If I am understanding this
correctly, another related missing functionality is that PostgreSQL does
not allow the old and new tables to be referenced for statement-level
triggers (i.e., the "OLD TABLE" that contains all the deleted/modified
rows in case of deletion/update). I think this is also worth noting as
any workaround for it seems to be more difficult (if possible at all)
than for the missing alias feature.
Regards,
Louis-Claude Canon