Re: Why no INSTEAD OF triggers on tables?

On 12/16/2013 07:53 PM, Robert Haas wrote:
> So, put a BEFORE trigger, and make it return NULL. Same effect,
> different notation.

NOT the same:

Master partition table with BEFORE trigger:

josh=# insert into a ( id, val ) values ( 23, 'test' ), ( 24, 'test'),
(25,'test');

INSERT 0 0
^^^

View with INSTEAD OF trigger:

josh=# insert into a_v ( id, val ) values ( 23, 'test' ), ( 24, 'test'),
(25,'test');

INSERT 0 3
^^^

The difference here is that the INSTEAD OF trigger returns a
rows-affected count, and the BEFORE trigger does not (it returns 0).
Some drivers and ORMs, most notably Hibernate, check this rows-returned
count, and error if they don't match the rows sent.

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com