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  1. #1
    Join Date
    Nov 2003
    Location
    Rotterdam, Netherlands
    Posts
    127

    Unanswered: Hit ratio in Oracle

    Hi,
    The hit ration in my ORACLE 8i DB was 67% so i increased the db buffer and restarted the database as it cannot be changed on the FLY.

    The hit ratio was 99% and a substantial improvement in performance was seen. Now i can see that in 2 days the hit ration has reduced to 85%

    IS there any setting for cleaning up the db buffers?
    Please guide me in this.

    Thanks

  2. #2
    Join Date
    Dec 2002
    Location
    Netherlands
    Posts
    118
    No, there is no such thing like

    alter system flush buffer_pool...

    You'll want to work with a buffer pool keep to influence the way the buffer pool keeps and flushes buffers.


    Good luck

    Remi
    Remi Visser

    Oracle Database Administrator
    (OCP certified 8i)

    Homepage: http://home.remidian.com/

  3. #3
    Join Date
    Jul 2003
    Posts
    2,296
    How about doing a statspack report (30 minute interval) and checking the hit-ratio for that timeframe? That would seem to be a more realistic analysis rather than looking at what the hit ratio was for a 2 day period.
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  4. #4
    Join Date
    Aug 2003
    Location
    Where the Surf Meets the Turf @Del Mar, CA
    Posts
    7,776
    Provided Answers: 1
    Buffer Cache Hit Ratio is a bogus indicator of performance.

    http://www.hotsos.com/dnloads/1.Mill...CacheRatio.pdf

    http://www.ixora.com.au/scripts/cache.htm
    tunable_cache_miss_rate.sql can be used to achieve any BCHR you want

  5. #5
    Join Date
    Nov 2003
    Location
    Rotterdam, Netherlands
    Posts
    127
    Thank you all

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