Re: Causes for high "Rollback per transaction %" in AWR report
- From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
- To: <thomas.kellerer@xxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 20 Nov 2012 14:37:38 -0000
----- Original Message -----
From: "Thomas Kellerer" <thomas.kellerer@xxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Tuesday, November 20, 2012 2:16 PM
Subject: Causes for high "Rollback per transaction %" in AWR report
| Hello,
|
| I am analyzing some performance problems of an Oracle 10.2.0.5.0 2-node
RAC system and one figure in the AWR report caught my attention:
|
| Rollback per transaction %: 98.15
|
| What exactly does this figure indicate, and what factors contribute to
this?
|
The first things to check are the stats:
rollback changes - undo records applied
user commits
user rollbacks
transaction rollbacks
If the first figure is very small it doesn't really matter how many
rollbacks you are doing, they are "no work" rollbacks. It is a common
feature of web app servers to issue a (redundant) rollback after every
single statement sent to the database - you may be seeing the effects of
such a WAS.
If transaction rollbacks is much larger than user rollbacks then there may
be an internal problem of some sort - e.g. a loader program is constantly
trying to insert duplicate keys which are rolled back by Oracle, raising an
error that should be trapped (but might be ignored) by the application.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com/all-postings
Author: Oracle Core (Apress 2011)
http://www.apress.com/9781430239543
--
//www.freelists.org/webpage/oracle-l
Other related posts:
