Re: Hash Joins and Sort Merge - When to use?

SPAMBLOCK.Maxwell_Smart_at_ThePentagon.com.SPAMBLOCK (Brian Tkatch) wrote in message news:<3c43043d.550031532_at_news.alt.net>...
> On 14 Jan 2002 07:35:21 -0800, trundlebus1_at_hotmail.com (Ian) wrote:
>
> >I'm doing some research into Hash Joins and Sort Merge Joins and was
> >wondering if any of you could explain what situations each type of
> >join is best for and how I could test this?
> >
> >I have searched the internet to find literature but haven't found much
> >yet so if anyone knows of any good sites please let me know
> >
> >Thanks in advance
> >
> >Ian
>
> Check out
> <URL:http://otn.oracle.com/docs/products/oracle8i/doc_library/817_doc/server.817/a76992/optimops.htm#39473>
>
> Oracle8i Designing and Tuning for Performance
> Release 2 (8.1.6)
> Part Number A76992-01
> Chapter 4, "The Optimizer"
> Section: Optimizing Joins
> Sub-Section: How the Optimizer Chooses the Join Method
>
> where it shows how the CBO estimates the cost of each and decides
> which one to use.
>
> For a discussion of the different types of joins, see the preceding
> sub-section, "Join Operations".
>
> Brian

Brian,

Thanks for the reply! That site is proving to be very useful.

I have decided to use the Wisconsin data model to create 4 relations - 2 large and 2 small. I will then join these relations to using Hash and Sort Merge, to find which is most efficient when joining a large and a small relation or 2 large relations and so on.

Does this kind of comparison sound feasible?

Thanks Received on Tue Jan 15 2002 - 12:45:31 CST