Determine in a trigger if UPDATE query really changed anything

Hi!

Currently I am doing:

CREATE TRIGGER some_trigger AFTER UPDATE ON my_table REFERENCING NEW
TABLE AS new_table OLD TABLE AS old_table FOR EACH STATEMENT EXECUTE
FUNCTION my_trigger();

In my trigger I do:

PERFORM * FROM ((TABLE new_table EXCEPT TABLE new_table) UNION ALL
(TABLE new_table EXCEPT TABLE old_table)) AS differences LIMIT 1;
IF FOUND THEN
...

But I wonder if there is an easier way. I would just like to know if
an UPDATE really changed anything.

For DELETE I do "PERFORM * FROM old_table LIMIT 1" and for INSERT I
do "PERFORM * FROM new_table LIMIT 1" and I think this is reasonable.
Still, not sure why I have to store the whole relation just to know if
statement really changed anything.

Mitar

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