Buffer Cache
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Thread: Buffer Cache

  1. #1
    Join Date
    Apr 2001
    Posts
    112
    On my 8172 database the db_block_size is 8K.
    db_block_buffers is 100000

    I was checking the stats of a particular session which seems to be stuck, I noticed the
    buffer is not pinned count=265385370

    What does this suggest?

    Thanks

  2. #2
    Join Date
    Sep 2001
    Location
    Dallas, TX
    Posts
    27

    Buffer is pinned count

    This stat essentially counts the number of times a buffer was free when visited. This does not affect the appication.

    BK.

  3. #3
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
    Posts
    3,938
    Why 100000? How much memory do you have?


  4. #4
    Join Date
    Apr 2001
    Posts
    112
    4GB of RAM.

    Another point is , my shared_pool_size is set to be 539MB, is it appropriate to have such a large size?

  5. #5
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
    Posts
    3,938
    It is big. Often DBAs increase the shared pool for some reasons (latch contention, etc). But this can delay the onset of shared pool latch contention and at the end exacerbates it.
    Increasing the the shared_pool size is not going to account for SQL that is not shared. This will be causing a poor hit ratio from v$librarycache.

    Do you have only one instance running? Note that the maximum size of SGA depends upon the OS limits and the kernel paramters that are set.


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