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Re: Performance Predictions - How to?

From: Mark D Powell <Mark.Powell_at_eds.com>
Date: 22 Dec 2006 08:52:16 -0800
Message-ID: <1166806335.849852.271960@73g2000cwn.googlegroups.com>

On Dec 22, 10:23 am, "EscVector" <J..._at_webthere.com> wrote:
> I have a multiple part process and I'm able to predict runtime based on
> record count within +-30 minutes. The prediction is made by taking the
> total to-be-processed record count from the longest single process and
> dividing it by the runtime total of all processes.
> How is this mathematically possible/sound? This isn't even a linear
> projection. Just dumb luck?
>
> I'm looking for ways to project performance based on record counts, so
> any suggestions are welcome.

Table A and B both have 1 million rows. Table A has a row length of 20 bytes. Table B has a row length of 2000 bytes. Do you think the time to process 500,000 rows of Table A will be the same as to process 500,000 rows of Table B? It could be if the 500k access were by PK in randon order. But if full table scans are used I would expect the 20 byte row task to run in less time.

A + or - estimate of 30 minutes is not very good for a job that runs one hour but is pretty good for a job that runs 24 hours so your current method may or may not be working very well. You did not provide any information to how accurate 30 minutes is.

If you compare prior runs of a job to current runs where the row count varied then using row count will probably work fairly well, but using an average row count number for all jobs is likely to, at least in a few circumstances, miss the mark badly. How badly will depend on how similar your jobs are.

You are likely to have better luck estimating the number of blocks of data that each job has to read and basing the estimate off of this.

HTH -- Mark D Powell -- Received on Fri Dec 22 2006 - 10:52:16 CST

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