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RE: Statspack Intervals

From: MacGregor, Ian A. <ian_at_SLAC.Stanford.EDU>
Date: Wed, 10 Jul 2002 08:13:25 -0800
Message-ID: <>

Statspack is a very nice tool, however if one really wants to find problems lurking in a database even five minute intervals can be too long. By finding problems I mean locating inefficiencies proactively. As good as the first few chapters of "Database Tuning 101" are, the book preaches a reactive and not a proactive tuning method. Both are needed.  

I have reached the conclusion that some data such as that in V$SESSION_WAIT and V$SQLTEXT should be collected each minute. I don't mean to collect everything just the active sessions and those that have been idle for a minute or less. It would be nice to collect session stats every minute as well, but that becomes too expensive. I choose to collect the session stats which best mirror what tkprof puts out.  

Running statspack is not ideal for this. It will record information which I do not need that fine-grained. I do however need it for comparison purposes.  

I can better answer questions such as who is accessing the data, what fields are being accessed, what is the query plan used, how expensive is the access, etc. I can also better answer questions, such as, "One of my overnight jobs ran very slowly, can you tell me why?"

Much of this monitoring could be replaced by proper code review.  

Ian MacGregor
Stanford Linear Accelerator Center <>    

-----Original Message-----
Sent: Wednesday, July 10, 2002 3:33 AM
To: Multiple recipients of list ORACLE-L


The rule of thumb is:  

Monitoring: 15 to 30 minute interval  

Problem solving: 5 to 15 minute interval.  

Really wrong are intervals of an hour or so(only usefull for comparision)  



I've just been rolling out statspack against all of our production DBs. What I am not sure about is how often I should take a snapshot ? I am planning on holding one months worth of data and then backing it up and then purging.  

How often do you guys take snapshots and does my history/purge plan sound reasonable.  

Regards and TIA  


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Author: MacGregor, Ian A.
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