Re: Response time analysis and TKPROF

If someone were to ask me whether a TKPROF report tells you anything about wait events, my first response would be No.

Yet what, if anything, can I learn from a quick glance at the totals for "CPU time" and "elapsed time"? If...

response time = service time + wait time

.... then is it correct to say:

• response time is: TKPROF total elapsed time
• service time is: TKPROF total CPU time
• wait time is: TKPROF total elapsed time - total CPU time

If this is true, then from a TKPROF report, I could glance at these two totals and see whether wait events are significantly affecting the SQL statement.

Case #1: The two totals are very close. Waits are not affecting this SQL statement.

Case #2: Total CPU time is significantly less than total elapsed time. Waits are significantly affecting the statement. Consider running the SQL in a stand alone session, and use before and after snapshots of v$session_event to see what it's waiting on.

Are my assumptions true? And as Stephane points out, even if they are true, are they of any practical value? Personally, I think it would be kind of cool to be able to look at a TKPROF report and get a quick read on whether wait events are significantly affecting this particular SQL statement.

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Author: Greg Moore
  INET: sqlgreg_at_pacbell.net

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