RE: WAITS

> Each morning I produce graphs...

I think this is key. Having historical data graphically presented helps to establish the norm and when there may be performance issues to investigate. This follows step 2 of Gaja's "Oracle Performance Tuning 101 Methodology" which says, "Measure and document current performance."

To do this I created a DBA monitoring HTML display tool which gets data from V$SYSSTAT and V$SYSTEM_EVENT once a minute, stores it in a round robin database and displays it with RRDTool. I've accumulated 2 months of this data and it's amazing how lightweight it is. With graphs it's easy to see when something's amiss. We capture expensive SQL via StatsPack every 15 minutes and I have correlated a spike on a graph to specific SQL executed 2 hours earlier.

Now I'm trying to decide on my next enhancement: 1) HTML/GUI interface to StatsPack data or; 2) Drill down to V$SESSION_WAIT ???

Steve Orr
Bozeman, Montana

-----Original Message-----
Sent: Thursday, May 09, 2002 5:23 PM
To: Multiple recipients of list ORACLE-L Importance: High

In general There are two problems in using the "top five waits" out of statspack: it reports idle waits; no matter how well-tuned your database there will always be a top five. The numbers presented show total time-waited in csecs for the time period. As Jared said we don't know the time period. We don't know the average wait time.

I have learned some rudimentary gnuplot skills. Each morning I produce graphs of what went on the in the databases the previous day on and hour by hour basis. If something is really askew I break the hour down into ten minute blocks. This helps me to better recognize patterns of database usage.

Ian MacGregor
Stanford Linear Accelerator Center
ian_at_slac.stanford.edu

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Author: Orr, Steve
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