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Re: Performance Monitoring

From: Jan Krueger <>
Date: Fri, 28 Sep 2007 14:40:20 +0200
Message-ID: <46fcf5a0$0$29372$>

joel garry wrote:
> On Sep 26, 1:41 am, Stefan Wetter <> wrote:
> 1. Read Concepts manual.
> 2. Understand that most performance issues come from application
> issues. For example, if some silly SQL reads an entire table to get a
> few rows, you wil likely have a lot of unnecessary I/O that won't fill
> up the SGA.
> 3. Read the Performance manual.
> 4. Understand the optimizer. It can only use the information it is
> given. If the statistics it uses are wrong, non-existent, or skewed
> in a manner the optimizer doesn't know about, it can choose a silly
> plan for accessing the data. Sometimes a full table scan is not
> silly.
> 5. Understand what plans are and how to use them to understand 4.
> 6. Understand what statspack (or other tools such as Jerome
> mentioned) can tell you.
> 7. Understand when, how and why to use tracing.
> 8. Understand what waits are and how to evaluate them.
> 9. Read and work through books and articles by Jonathan Lewis, Tom
> Kyte, and Cary Milsap. (And I still like Lawson's book for the basic
> how-to-dba implicit in your question, though it is out of date now).
> 10. Understand why rules of thumb can be a bad idea for improving the
> database of customers.
> 11. Understand that tools based strictly on Oracle can be a bit
> misleading from a systems standpoint, and systems tools can be
> misleading from Oracle's viewpoint. Simply knowing you have a lot of
> reads does not mean anything is wrong, after all, what is a database
> going to be used for? A proper tuning methodology will figure out
> what critical bottlenecks are, and what to do about them.
> 12. Understand the basics. For example, if you have sequential write-
> intensive archive writing interfering with random reads and writes for
> undo and everything else, thrashing a SAN cache, you probably have a
> configuration problem. If you have multiple users accessing data, you
> need to understand how Oracle handles the issues involved.
> 13. Create clear metrics for performance improvement.
> 14. Read Concepts manual.
> 15. Iterate.

I will print this and put it at my office wall in a frame.

Never read good advise for performance problems in such a condensed way before.

Jan Received on Fri Sep 28 2007 - 07:40:20 CDT

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