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  1. #1
    Join Date
    Jan 2003
    Location
    Zutphen,Netherlands
    Posts
    256

    Unanswered: deadlock on DB2 7.1 with ETL-tool

    During nightly sessions I am experiencing deadlock issues that are recorded in my ETL log as follows:

    Code:
    READER_1_2_1> Mon Nov 08 20:47:34 2004
    READER_1_2_1> RR_4035 SQL Error [
    [IBM][CLI Driver][DB2/NT] SQL0911N  The current transaction has been rolled back because of a deadlock or timeout.  Reason code "2".  SQLSTATE=40001
    
     sqlstate = 40001
    
    Database driver error...
    Function Name : Execute
    SQL Stmt : SELECT BIKE_ITEM_MASTER.IPROD FROM BIKE_ITEM_MASTER
    Deadlock error encountered.
    Database driver error...
    Function Name : Execute
    SQL Stmt : SELECT BIKE_ITEM_MASTER.IPROD FROM BIKE_ITEM_MASTER
    Deadlock error encountered.].
    READER_1_2_1> Mon Nov 08 20:47:34 2004
    READER_1_2_1> BLKR_16004 ERROR: Prepare failed.
    WRITER_1_2_1> WRT_8333 Rolling back all the targets due to fatal session error.
    WRITER_1_2_1> WRT_8325 Final rollback executed for the target [SFCC_COMBINATIONS] at end of load
    WRITER_1_2_1> WRT_8035 Load complete time: Mon Nov 08 20:47:34 2004
    I have not changed the isolation level of the connection yet (CS as yet), but would changing it to UR resolve this. What would be possible drawbacks?
    Ties Blom
    Senior Application Developer BI
    Getronics Healthcare
    DB2,ORACLE,Powercenter,BusObj,Access,
    SQL, SQL server

  2. #2
    Join Date
    Jan 2004
    Location
    Europe, Finland, Helsinki
    Posts
    64
    Yes!

    A Change to UR should solve your deadlock problems! However, you may have some other problems. The biggest problem is that you may then be reading a "ghost" row, because transaction inserting this new row, did a rollback.

    We have found that in our environment a rollback is such a rare feature, that for the DW-data this kind ghost rows are "acceptable risk". This risk may be lessened if you can avoid reading the most active data. But if you are reading non-active data - then no deadlocks should occur!

    Cheers, Bill

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