Re: Hash Joins vs. Nested Loops

Ryan Gaffuri wrote:

> Someone I was working with told me the following. I was wondering if
> anyone has any comments, because I have not seen this in any
> articles/books.
>
> He said that when he tunes he generally likes to try to force nested
> loop joins over hash joins because these tend to increase performance?
> He has done this for a long time and he said that is based on
> experience.
>
> Anyone else notice this? I have never seen this anywhere else. BTW, I
> know the difference between hash joins and nested loops and know when
> either is generally used by the optimizer.

As a generic statement I would give in little credence just as the oft repeated "put tables in one tablespace and indexes in another". One should never tune to a rule ... but rather tune each and every single statement based on the statistics and optimizer under which it will be run.

Even if he is correct 90% of the time ... that is not enough.

Daniel Morgan Received on Fri Feb 21 2003 - 15:16:47 CST