RE: Oracle aborts monitoring a long running statement - how to find the reason

Why not trace the session and determine what it doing? What does v$session or ASH say the query is waiting on? Can you pull the active plan that is being used from v$sql_plan to determine what it is doing?

Matthew Parker
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-----Original Message-----

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Thomas Kellerer Sent: Wednesday, December 6, 2017 12:01 AM To: oracle-l_at_freelists.org
Subject: Oracle aborts monitoring a long running statement - how to find the reason

Hello list,

we are trying to troubleshoot a complicated query that used to run in under an hour and started to get extremely slow for unknown reasons ("extremely slow" means, it still isn't finished after 8 hours)

Oracle did not monitor the statement even though it was running very long and was using parallel execution.

In MOS we found that only statements with a plan shorter then 300 lines are monitored. We were able to change the parameter "_sqlmon_max_planlines" to 500 as suggested in DocID: 1613163.1.

Now Oracle indeed _starts_ to monitor the statement. But after an hour or so, the status of the session(s) turns to "DONE (ERROR)" in v$sql_monitor, but the query keeps on running, so I am confused what the "ERROR" means there.

My idea was to use the information provided by the real time monitoring to find the bottleneck of the statement but if it stops, this isn't really helpful.

Is there any view where I can find the _reason_ for the "(ERROR)" or the reason why Oracle stops monitoring the statement? v$sql_monitor.error_message and v$sql_monitor.error_number are null for the sessions of that statement

This is on a 11.2.0.3 EE running on Linux (please don't comment on the old version - this is a hosted environment of one of our customers. At least an an upgrade to 11.2.0.4 is planned).

Thanks
Thomas

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http://www.freelists.org/webpage/oracle-l Received on Wed Dec 06 2017 - 09:10:56 CET