RE: Good Performance

  • From: "Christian Antognini" <Christian.Antognini@xxxxxxxxxxxx>
  • To: <Jeff.Wiegand@xxxxxxxxxxx>
  • Date: Wed, 20 Apr 2005 20:17:26 +0200

Hi Jeff

>Could someone give me some "benchmarks" defining good performance?

Performance is good when end-user expectations are met.

>What is a good benchmark for determining if a query is doing too many
>buffer reads, or too many disk reads? Is 10,000 buffer reads considered
>high, or is it 1,000,000? Or does it matter if, on the overall, things
>kick butt.

It really depends... eventually even 1 LIO is too much. This is the case =
when it is not necessary to run the query!

Personally I usually give a look to the number of LIO per row. If this =
value is smaller than 5 it is usually ok, if it is larger than 20 it is =
normally bad. Everything in between should be analyzed.

>This is a half hour window during peak usage. Is anything way off?

More information is needed... e.g. how many CPU has your system?


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