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Thread: Fixed and variable size in sga

  1. #1
    Join Date
    Sep 2000
    Posts
    362

    Red face

    Hi,
    What is the Fixed Size and the variable Size in the output when you give the show sga command.

    SQL> show sga

    Total System Global Area 217520156 bytes
    Fixed Size 75804 bytes
    Variable Size 79519744 bytes
    Database Buffers 137846784 bytes
    Redo Buffers 77824 bytes

    Thanks
    Anurag

  2. #2
    Join Date
    Oct 2000
    Location
    Saskatoon, SK, Canada
    Posts
    3,925


    Different sub-divisions of the SGA
    ----------------------------------

    Sample from svrmgrl SHOW SGA:

    Total System Global Area 23460696 bytes
    Fixed Size 72536 bytes
    Variable Size 22900736 bytes
    Database Buffers 409600 bytes
    Redo Buffers 77824 bytes

    Total System Global Area
    -Total in bytes of all the sub-divisions that makes up the SGA.

    Fixed Size
    -Contains general information about the state of the database and the instance,
    which the background processes need to access. No user data is stored here.
    This area is usually less than 100k in size.

    Variable Size
    -This section is influenced by the following init.ora parameters
    shared_pool_size
    large_pool_size
    java_pool_size
    See 'Approximationg size of the SGA' section for version specific information.

    Database Buffers
    -Holds copies of data blocks read from datafiles.
    size = db_block_buffers * block size

    Redo Buffers
    -A circular buffer in the SGA that holds information about changes made to
    the database. Enforced mininum is set to 4 times the maximum database block
    size for the host operating system.

    Thanx
    Sam



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