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Real Application Testing Hangs on Replay

Oracle Version: 11.2.0.3
Platform: Windows Server 2003 SP2

The Problem

I was using Real Application Testing, and more specifically the Database Replay tool to get some performance comparison testing done. When running the replay it appeared to hang. I had changed one thing, and that was the following hidden parameter “_disable_flashback_archiver”.

This is a hidden parameter in the Oracle 11g DB which is used to enable or disable a new background process called Flashback Data Archive FBDA which is in use when you are using “Total Recall”. I have written another article on how you can find out the values of the hidden parameters in your Oracle DB.

The Cause

I read through an Oracle white paper and the testing that they carry out in this article suggests that if Total Recall is not in use you can disable the feature by setting this parameter to 1. The default is 0, meaning that it is enabled.

I was testing the performance impact of disabling this setting when replaying a captured workload into a DEV system in order to test the performance of my freshly upgraded 11g DB. This seems to have been the cause of the hang, because subsequent replays with the “_disable_flashback_archiver” set to 0 all worked.

The Solution

This is a lesson in not playing around with the hidden parameters…

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Category: RAT


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