Re: SQL Performance question

Dag Arne Matre wrote:
>
> If memory serves me right, this:
> ... WHERE EXISTS ( ....
> would normally perform better than
> ... WHERE <column> IN ( ...
>
> I have an example of the opposite, which is confirmed by EXPLAIN PLAN (there
> is a table scan in the EXISTS version). So, I wonder:
> - memory serves me wrong
> - this used to be true, but not anymore
> - this is normally true, it is probably just wrong for this exact statement
> - other?
>
> Oracle 8.0.5.
>
> TIA,
> D A

This typically used to be the case - optimiser improvements in Oracle means that its often smart enough to change a 'where in' to a join (which can be better than where-exists)

HTH

-- 
===========================================
Connor McDonald
http://www.oracledba.co.uk

We are born naked, wet and hungry...then things get worse