Rollback Contention

From: Erik Williams <ewilliams_at_brownco.com>
Date: Mon, 17 Jun 2002 11:33:31 -0800
Message-ID: <F001.0047F7C8.20020617113331@fatcity.com>

I have a couple of Statspack questions related to rollback contention. I have found some hints to their meanings on Metalink, but am still fairly in the dark. Any clarification would be greatly appreciated. Also, can anyone recommend the new Statspack book?

1. The transactions per second in the load profile reads 133. Does this mean that over the length of the stats report period, the number of transactions completed divided by the number of seconds equals 133? Is there a way of determining the average number of consecutive transactions? This would be a good number to know in looking at the contention of rollback segments. I have read that between one and four is a good target for concurrent rollback segment use.
2. Rollback / transaction Pct reads 0.03. I currently have 10 RBS. Does this mean that, on average, 300 transactions are using each RBS -> 10/300=0.03?
3. All of the rollback segments show 0.00 pct waits. There are some waits for undo header buffers. How do the two of these measures correlate? Why would one be zero and the other nonzero? Would increasing the number of segments reduce the undo header buffer waits?

Thanks again.
Erik

--

Please see the official ORACLE-L FAQ: http://www.orafaq.com
--

Author: Erik Williams
  INET: ewilliams_at_brownco.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
--------------------------------------------------------------------

To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Mon Jun 17 2002 - 14:33:31 CDT