Tuesday, 17 April 2018

Important properties a schedule of transactions must have to maintain a database in a consistent state



What are the important properties a schedule of transactions must have to maintain a database in a consistent state?


Properties of a schedule of transactions

We need a schedule which

  • is serializable 
    • a concurrent schedule which produces same result as a serial schedule is called serializable schedule

  • is recoverable 
    • a schedule with the ability to recover from failures

  • is cascadeless 
    • a schedule that avoids/eliminates cascading rollback in case of aborting of one or more transactions.

  • preserves the order of the operations in each of the individual transactions

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important properties of schedules in dbms

why a schedule need to be serializable

cascadeless schedules

preserving the consistency of a database

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