Re: Shouldn't "WHEN (OLD.* IS DISTINCT FROM NEW.*)" clause be independent from data type? - Mailing list pgsql-general

On 09/17/2015 06:32 AM, Albe Laurenz wrote:

pinker wrote:

I've tried to write audit trigger which fires only when data changed, so I used "WHEN (OLD.* IS
DISTINCT FROM NEW.*)" clause as described in documentation
<http://www.postgresql.org/docs/9.4/static/sql-createtrigger.html> . Should this clause be independent
from data type? because an error occurs when I'm trying to modify row with point data type: ERROR:
could not identify an equality operator for type point

I guess it is dependent on data type as it requires an equality operator,
and type "point" doesn't have one.

To echo the OP, why is that?

http://www.postgresql.org/docs/9.4/interactive/functions-comparison.html

For non-null inputs, IS DISTINCT FROM is the same as the <> operator.

So:

test=> select '(1,2)'::point <> '(1,2)'::point;
 ?column?
----------
 f
(1 row)

test=> select '(1,2)'::point <> '(1,3)'::point;
 ?column?
----------
 t

test=> select '(1,2)'::point <> null;
 ?column?
----------

(1 row)