RE: Performance off "count(*)"

From: Tanel Poder <>
Date: Sun, 20 Jul 2008 17:42:09 +0800
Message-id: <79E78780D0074051BCF66C1F26A82A08@windows01>

> 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...


Received on Sun Jul 20 2008 - 04:42:09 CDT

Original text of this message