[HACKERS] Strange behavior on plpgsql trigger function in if comparison

[Omar Bettin]

Hi,

I have to compare an OLD.Value with a NEW.Value on PostgreSQL 8.2.4 plpgsql 
trigger function:

IF OLD.Value <> NEW.Value THEN
...

but, if OLD.Value IS NULL and NOT NEW.Value IS NULL the previous IF does not 
work and I have to use this method:

IF (OLD.Value <> NEW.Value) OR (OLD.Value IS NULL  AND NOT NEW.Value IS NULL) 
THEN
...

this works!
Is that normal ?

Thank you

Omar Bettin