Data Cache Hit Ratio
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Thread: Data Cache Hit Ratio

  1. #1
    Join Date
    Mar 2005
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    143

    Data Cache Hit Ratio

    I was reading up on tips and techniques for performance tunning databases. I got to a section that talked about Hit Ratio and using it to track performance. I was wondering if anyone uses it and could elaborate on their experience with it. I am 10g release level is 10.2.040 and we are in a UNIX AIX environment. My production database is about 140 gigs. I have been the DBA here for about a month or so and the don't really complain about DB performance (knock on wood). I have een monitoring the system and don't really see any spikes in performance. I am just trying to be pro-active

  2. #2
    Join Date
    Mar 2007
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    Ft. Lauderdale, FL
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    In short... If it's not broken, don't try to fix it

    Performance tunning has moved long ago from focusing on hit ratios to focusing on wait events.

    Having said that, it doesn't hurt to track hit ratios - in posters particular case there are not apparent performance issues so whatever hit ratios poster sees today can be used as a baseline for future reference.
    Pablo (Paul) Berzukov

    Author of Understanding Database Administration available at amazon and other bookstores.

    Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.

  3. #3
    Join Date
    Oct 2006
    Posts
    175
    Quote Originally Posted by jayjabour View Post
    I was reading up on tips and techniques for performance tunning databases. I got to a section that talked about Hit Ratio and using it to track performance. I was wondering if anyone uses it and could elaborate on their experience with it. I am 10g release level is 10.2.040 and we are in a UNIX AIX environment. My production database is about 140 gigs. I have been the DBA here for about a month or so and the don't really complain about DB performance (knock on wood). I have een monitoring the system and don't really see any spikes in performance. I am just trying to be pro-active
    I'd add that cache hit ratios vary in different scenarios and depend heavily on application design. Well as already PAVB mentioned, you can log these parameters in different intervals and baseline them. Comparing them in different intervals will surely help you in future if you needed to tune them.

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