RE: Performance off "count(*)"
Date: Sun, 20 Jul 2008 17:42:09 +0800
> Also (as Chris mentioned), looks like the count(*)
> optimization is that Oracle can skip the row data. Which it
> can never do for count(col) as this is semantically different
> from count(*) - NULL columns aren't counted when using count(col):
Commentig my own post - of course when there's a valid not null constraint in place on the column col, then Oracle can use the count(*) "optimization" for count(col) statements too...
Tanel.Received on Sun Jul 20 2008 - 04:42:09 CDT