Question about buffer_pool_keep and recycle_keep
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Thread: Question about buffer_pool_keep and recycle_keep

  1. #1
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    Question about buffer_pool_keep and recycle_keep

    Hi, i dont know to much about tunning of Oracle 9i databases, i was trying to search something about this 2 parameters od init.ora :

    1. buffer_pool_recycle
    2. buffer_pool_keep

    anyone can explain me a little about this 2 parameters and how can be used?

    thanks
    Gustavo Villaran

  2. #2
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    sorry i wa trying to say:

    db_keep_cache_size
    db_recycle_cache_size

    thanks
    Gustavo Villaran

  3. #3
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    try tahiti.oracle.com

    that's not new feature, it's there since Oracle 8.0.3

  4. #4
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    Ok to explain a little.

    Use KEEP Pool to cache small tables and use RECYCLE pool to cache large tables.
    Amar
    "There is a difference between knowing the path and walking the path."

    Amar's Blog  Get Firefox!

  5. #5
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    Originally posted by adewri
    Ok to explain a little.

    Use KEEP Pool to cache small tables and use RECYCLE pool to cache large tables.
    Really? RECYCLE pool to cache large tables? Great...
    Oracle Certified Master
    Oracle Certified Professional 6i,8i,9i,10g,11g,12c
    email: ocp_9i@yahoo.com

  6. #6
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    Originally posted by julian
    Really? RECYCLE pool to cache large tables? Great...
    Why, why not ??

    KEEP pool, is meant to keep 'warm' and 'hot' blocks cached for as long as possible. In the RECYCLE pool, the aim is to age out a block as soon as it is no longer needed. This is advantageous for 'large' tables that are read in a very random fashion. If the probablity that a block will ever be re-read in a reasonable amount of time, there is no use in keeping this cached block for very long.

    Of course you cannot define a large table. Only way to see which tables to keep in

    o The KEEP pool
    o The RECYCLE pool
    o The DEFAULT pool

    is to take statspack reports now and for a couple of days and then compare to see if there is any improvement. If the report improves then right tables have been moved in otherwise not.

    More ever caching large tables (which face random full table scans) will benefit because when loading a full large table scan blocks, the blocks that has been cached earlier are pushed out to accomodate space for this full table scan. In order to prevent this, cache such large tables to RECYLE so that the pushing out of already cached important data is prevented.

    I hope im clear. What's your point ?
    Last edited by adewri; 06-09-2003 at 01:45 AM.
    Amar
    "There is a difference between knowing the path and walking the path."

    Amar's Blog  Get Firefox!

  7. #7
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    pando,

    Are you sure it is avaliable in 8.0.3? I thought it is a
    9i new feature.

    I tested on 817, it is not there:

    SQL> show parameter db_keep_cache_size;
    SQL>
    SQL> select value from V$parameter where name='db_keep_cache_size';

    no rows selected

    SQL>

  8. #8
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    in 8i i think is buffer_pool_keep and buffer_pool_recycle
    Gustavo Villaran

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