help! concurrency problem

• zyc

  Grasshopper

  Points: 11

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  June 18, 2004 at 1:43 am

  #83240

  I have 2 transactions running with concurrency problem:

  Transaction T1:

    1) set transaction isolation level @isolationLevel

    2) begin transaction

    3) select * from vendor

       ----wait 1----

    4) update companyInfo set AddrL1='stree 1'

       ----wait 2----

    5) rollback

  Transaction T2:

    1) set transaction isolation level @isolationLevel

    2) begin transaction

    3) select * from companyInfo

       ----wait 1----

    4) update vendor set name='vendor 1' where code = '021009'

       ----wait 2----

    5) rollback

  situation 1 :  @isolationLevel =  read committed

   I run T1 to wait2, then i try to run T2,the T2.step3 is blocked.

  situation 2 :  @isolationLeve2 =  repeatable read OR serializable

   I run both T1 and T2 to wait1. after that, I try to run both T1 and T2 to wait2,but they deadlocked

   

  I do not want the read/write block write/read,how can I implement that ? ( i do not want set  read UNcommitted )

  How can I set the default Pessimistic concurrency to Optimistic ?

  thanks in advance

• sa24

  SSCrazy Eights

  Points: 8027

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  June 18, 2004 at 12:13 pm

  #511097

  You can set the DEADLOCK_PRIORITY to LOW for T1 so that it does not block T2.