INCREASING LATCH HIT RATIO
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  1. #1
    Join Date
    Mar 2002
    Posts
    171
    Dear friends,

    When I execute:

    SELECT (1 - (Sum(misses) / Sum(gets))) * 100
    INTO v_value
    FROM v$latch;
    DBMS_Output.Put('Latch Hit Ratio : ' || Format(v_value));


    I am getting a very low value (less than 70%). I don't see any parameter in the INIT.ORA file to increase the number of latches.


    Kindly advise me how to increase the latch hit ratio. Your help will be appreciated.



  2. #2
    Join Date
    Oct 2000
    Posts
    467
    db_block_lru_latches is the parameter. (this is for db block buffers only)
    t
    Vinit

  3. #3
    As I know, in Oracle 9i you do NOT tune the latches.
    ovidius over!

  4. #4
    Join Date
    Sep 2001
    Location
    NJ, USA
    Posts
    1,287
    Originally posted by ovidius
    As I know, in Oracle 9i you do NOT tune the latches.
    In Oracle 7,8,8i this parameter has name db_block_lru_latches
    In Oracle 9i --> _db_block_lru_latches

    Default value of this parameter(s) is #CPU/2
    Max value for db_block_lru_latches is:
    Oracle 7 --> 2*#CPU
    Oracle 8,8i --> 6*#CPU
    I don't sure about 9i (_db_block_lru_latches) but probably max vallue more then
    6*#CPU

    --------------------------------------------------
    Addition (indirect) method for setup # of lru latches in 9i (8i):

    BUFFER_POOL_KEEP = {integer |(BUFFERS:integer, LRU_LATCHES:integer)}
    BUFFER_POOL_RECYCLE = {integer | (BUFFERS:integer, LRU_LATCHES:integer)}


    [Edited by Shestakov on 04-01-2002 at 11:35 AM]

  5. #5
    Join Date
    Mar 2002
    Posts
    171
    Originally posted by Shestakov
    Originally posted by ovidius
    As I know, in Oracle 9i you do NOT tune the latches.
    In Oracle 7,8,8i this parameter has name db_block_lru_latches
    In Oracle 9i --> _db_block_lru_latches

    Default value of this parameter(s) is #CPU/2
    Max value for db_block_lru_latches is:
    Oracle 7 --> 2*#CPU
    Oracle 8,8i --> 6*#CPU
    I don't sure about 9i (_db_block_lru_latches) but probably max vallue more then
    6*#CPU

    --------------------------------------------------
    Addition (indirect) method for setup # of lru latches in 9i (8i):

    BUFFER_POOL_KEEP = {integer |(BUFFERS:integer, LRU_LATCHES:integer)}
    BUFFER_POOL_RECYCLE = {integer | (BUFFERS:integer, LRU_LATCHES:integer)}


    [Edited by Shestakov on 04-01-2002 at 11:35 AM]
    Excellent Shestakov. Many thanks for the information.

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