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Date:         Fri, 11 May 2001 16:16:39 +0000
Reply-To:     Puddin' Man <pudding_man@POSTMARK.NET>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Puddin' Man <pudding_man@POSTMARK.NET>
Subject:      Re: Improve performance through  physical placement of indexes?
Comments: To: "Lewis, Dan BGI SF" <Dan.Lewis@BARCLAYSGLOBAL.COM>
Content-Type: text/plain; charset="iso-8859-1"

Lewis, Dan BGI SF wrote:

> I'd like to improve the performance of a WHERE clause that uses an index. In > the ancient olden days I could sometimes get dramatic performance > improvement by putting the index of a (non-SAS) file on a physically > separate drive from the data portion of the file. This could result in huge > performance improvements because it reduced the movement of the disk heads.

This is a good example of "thinking hardware" (to improve performance) on the part of the poster. Most commendable ...

> I wonder if I can do the same thing with SAS indexes under the Solaris OS?

I can't say for sure, but everything I've seen _suggests_ that SAS won't let you do this.

You've had several potentially helpful responses.

I'll only add that the onliest thing better than storing the index in memory is maybe storing both the index _and_ the data in memory.

If you are running SAS 8.1 or higher, I _think_ you _may_ be able to use the SASFILE statement, which is designed to load an entire SAS dataset into memory (if it's not too large).

I ran a simple test with Win2k/8.1: SASFILE _appears_ to make proper use of the index _and_ dataset in memory. "Quite speedy", it was.

Of course, you wouldn't wanna use SASFILE where the size of the index + dataset exceeds available physical memory.

Just another possibility ...

Zalut, Puddin'

******************************************************* *** Puddin' Man *** ***** ******************************************************;

"Rob the average man of his life illusion and you rob him of his happiness at the same stroke." - from "The Wild Duck", Henrik Ibsen, around 1885

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