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A summary of the schedules in this chapter

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• A summary of the schedules in this chapter
  • Consider the following 2 transcations:

    T1: w1(A) w1(B) c1 T2: w2(A) r1(B) c2

    Transaction T₁ will start first and transaction T₁ will read(B) written by transaction T₁:

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  • Recoverable schedule:

    Transaction T1 must commit before Transaction T2 can commit: Note: Transaction T2 can read dirty data !!!

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  • Avoid Cascading Rollback (ACR) schedule:

    Transaction T1 must commit before Transaction T2 can read: Note: Transaction T2 can not read dirty data !!!