Re: [COMMITTERS] pgsql: Add a WHEN clause to CREATE TRIGGER, allowing a boolean

Robert Haas <robertmhaas@gmail.com> writes:
> Random thought: would it be possible to use something like this to
> optimize foreign key constraints, by not firing them if none of the
> relevant columns have been updated?

There already is code in there to do that; see RI_FKey_keyequal_upd_fk
and RI_FKey_keyequal_upd_pk.

Earlier in the discussion of this patch I had suggested eliminating the
special-case code for FKs in favor of using a WHEN clause, but that
would probably not fly unless we can make the WHEN-based implementation
just as fast as the bespoke code; which seems unlikely.
        regards, tom lane