What did my MMON at point-in-time X?

Dear list,

I have a MMON question: MMON does, referencing the docs: "Capturing statistics value for SQL objects which have been recently modified" (among others).

I experienced a MMON-caused wait peak lately. The machine is rather poor for the purpose, and there have been lots of library cache latch waits as soon as MMON started its havoc. The application freezed as long as MMON did its business, after five minutes all stuff normalized. The v$session, the wait interface and ASH in general pointed out to "BEGIN stdContext.setSessionParameter(:1, :2, :3, :4, :5); END; " causing the trouble (latch: library cache"). But that's no real useful answer, so I am asking here:

How can I find out what MMON really did (or does)? If it just collected stuff about our object changes done before (index creation/rebuild, table commenting, gather_table_stats), it was okay, but I need to be sure that we will not freeze for another 5-minute-interval again "out of thin air".

Best regards and thanks in advance
Martin
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http://www.freelists.org/webpage/oracle-l Received on Wed Feb 18 2009 - 08:50:25 CST