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

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 Received on Mon Jan 14 2002 - 10:21:34 CST