Re: Improving Performance of Hash Joins

From: DA Morgan <>
Date: Thu, 25 Dec 2008 21:04:03 -0800
Message-ID: <> wrote:
> I am on Oracle on Windows 2003 32 bit. I have /3GB switch set
> on and have a value of sga_target set to 2.x GB,
> I am using a third party package and many queries are doing hash
> joins. I cannot modify any queries because of no source code available
> to me. I know in Oracle9i, there was some init.ora parameter for
> specifying memory used by hash joins which has been taken away in 10G.
> What are my options (if any) to improve performance of this hash joins
> which for some queries take 2-3 minutes.

Your assumption that you can not modify the queries is incorrect. You can easily do so with the DBMS_ADVANCED_REWRITE built-in package.

Go to Morgan's Library at and look up the package. The demo will show you how to do it.

Daniel A. Morgan
Oracle Ace Director & Instructor
University of Washington (replace x with u to respond)
Puget Sound Oracle Users Group
Received on Thu Dec 25 2008 - 23:04:03 CST

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