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Thread: Tuning PX Deq Credit: send blkd during Parallel Job Executions

  1. #1
    Join Date
    Sep 2008

    Tuning PX Deq Credit: send blkd during Parallel Job Executions

    Not a DBA, need some assistance,

    1) I am looking into possibilities to tune my parallel job processes. I have read to look into the pga_aggregate_size. Presently the size of PGA_aggregate_size is set to 125GB (the avilable memory in the box is 228GB).

    Total 100 connections are processing parallel jobs and are waiting on PX Deq Credit: send blkd.

    Do you think the value set to pga_aggregate_size is correct? Any suggestions.

    2) in 10g, I can not see any value set to my db_cache_size or shared_pool_size. Is it ok? For your reference I am pasting parameter details below ..

    ------------------------------------ ----------- bitmap_merge_area_size integer 1048576
    create_bitmap_area_size integer 8388608
    db_16k_cache_size big integer 0
    db_2k_cache_size big integer 0
    db_32k_cache_size big integer 0
    db_4k_cache_size big integer 0
    db_8k_cache_size big integer 0
    db_block_size integer 8192
    db_cache_size big integer 0
    db_keep_cache_size big integer 0
    db_recovery_file_dest_size big integer 2G
    db_recycle_cache_size big integer 0
    global_context_pool_size string
    hash_area_size integer 131072
    java_max_sessionspace_size integer 0
    java_pool_size big integer 0
    large_pool_size big integer 0
    max_dump_file_size string UNLIMITED
    object_cache_max_size_percent integer 10
    object_cache_optimal_size integer 102400
    olap_page_pool_size big integer 0
    parallel_execution_message_size integer 2152
    sga_max_size big integer 44128M
    shared_pool_reserved_size big integer 184M
    shared_pool_size big integer 0
    sort_area_retained_size integer 0
    sort_area_size integer 65536
    streams_pool_size big integer 0
    workarea_size_policy string AUTO

    Any help will be sincerely appreciated. Would like to reduce the PX Deq Credit: send blkd.


  2. #2
    Join Date
    Mar 2007
    Ft. Lauderdale, FL
    It is hard to believe in such a large environment you do not have a DBA at hand.

    When you have parallel jobs it is normal to see "PX Deq Credit: send blkd" event at the top or your list.
    Pablo (Paul) Berzukov

    Author of Understanding Database Administration available at amazon and other bookstores.

    Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.

  3. #3
    Join Date
    May 2000
    You cannot parallelize every single statement in Oracle. There are many restrictions imposed by Oracle.

    Why don't you post the slow performing "parallel Query" statements here?

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