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RE: Increasing Freelists?

From: Mohan, Ross <MohanR_at_STARS-SMI.com>
Date: Fri, 15 Jun 2001 12:24:46 -0700
Message-ID: <F001.0032BC1F.20010615120105@fatcity.com>

The table must be dropped, yes.

Default for table is 1 freelist, 2 for indexes.

This is not scientific ( both because there are no data to support it in your post and I have no hard perf data of my own ) but freelists are small and easily/rapidly maintained. Unless you have some sort of "niche-y" oddball application that needs every drop of space in a block, you can safely bump yourself up to 10 freelists on your hot tables. Maybe just a 2x or 4x on your less incandescent ones.

But, most important: for my money, LoadRunner does not always accurately simulate actual loads.

You might be tuning yourself away from a non-existent problem.

hth

-----Original Message-----
Sent: Friday, June 15, 2001 3:31 PM
To: Multiple recipients of list ORACLE-L

We've been load testing an application that will be allowing customers to enter their email information through the web. The loadrunner application was experiencing periodic freezing after which it would go back to normal. Reviewing the statspack information I saw a high number of buffer busy waits with the majority of the buffer waits being data block waits. This is not surprising, since the application is doing heavy inserts into several tables.
The recommendation from an article I have is to create multiple freelists for the tables undergoing heavy inserts. I've never done this before and I have no idea of how many to create. Increase the freelists from 1 to 2? More? What about freelist groups?

And am I correct that the table must be dropped and recreated to increase this parameter?

I was hoping to have read Gaja's book before I had to deal with this but it's still in the mail :).

Thanks in advance.
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Author: Miller, Jay
  INET: JayMiller_at_TDWaterhouse.com

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Author: Mohan, Ross
  INET: MohanR_at_STARS-SMI.com
Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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