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Message Posted: Thu, 25 Oct 2001 @ 17:37:16 GMT

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Subj:   Re: Performance
From:   Francesca Alfino


I do a lot of performance fishing... much of it involves narrowing down things by knowing what your system should look like. So your question is a good one but hard to give a general answer.

I use Teradata Manager a lot. PMON is good for blocking especially when it is many levels deep but you can get the same information from Teradata Manager Session Information. In SI I look at the active list sorted by delta CPU, multi sessions, blocking and summary or all sessions. You can keep all the screens open at the same time. I also keep queryman up so I can do debugging sql like checking the transient journal size, skewness of a table... Depending on the SI screens, I run SQL that helps verify or discount what I think I am seeing. For instance if you think someone is doing something on a particular table using the transient journal, you can try to see if you can read lock the table they are using. If you get the lock, it is not that person and you move on down the line.

The frequency a problem hits depends on the mix on your system.... This will change the order when you do your trouble shooting.

The top hitters in my mind are - - - >

- too much batch running or batch running with too many sessions (default is one per amp plus 2 to manage the rest)

- really skew sql or utilities

- blocking

- transient journal activity (bteq )

- sometimes even grants during the online day.

Hope this helps.


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