Transaction Locking Method Quiz
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Questions and Answers

What is the sequence of actions to modify a data item according to the text?

  • Lock (S), Write (X), Unlock (S)
  • Lock (X), Read (S), Unlock (X)
  • Lock (X), Write (X), Unlock (X) (correct)
  • Lock (S), Read (S), Unlock (S)

    • In transaction processing, what does it mean for a transaction to be 'well-formed'?

  • A transaction is well-formed if it constantly upgrades shared locks to exclusive locks.
  • A transaction is well-formed if it holds all data items in exclusive mode throughout.
  • A transaction is well-formed if it never locks a locked data item or tries to unlock an unlocked data item. (correct)
  • A transaction is well-formed if it locks every data item it encounters.

    • What access does a transaction have on a data item with an exclusive lock?

  • Read only
  • No access
  • Read and Write (correct)
  • Write only

    • Can multiple transactions hold shared locks simultaneously on the same item?

    <p>Yes, reads cannot conflict so more than one transaction can hold shared lock simultaneously on the same item.</p> Signup and view all the answers

    What is the purpose of upgrading a shared lock to an exclusive lock in some systems?

    <p>To enable write operations on the locked item by the transaction holding the lock.</p> Signup and view all the answers

    If T1 locks data item A in exclusive mode, what should T2 do when it wants to lock A?

    <p>It should wait for T1 to unlock A before proceeding.</p> Signup and view all the answers

    What is the purpose of the locking method in transaction processing?

    <p>To prevent concurrent access to shared resources during critical operations</p> Signup and view all the answers

    What does a shared lock allow in transaction processing?

    <p>Read operations on a data item by multiple transactions simultaneously</p> Signup and view all the answers

    When applying an Exclusive lock in transaction processing, what type of operation is allowed?

    <p>Preventing any write operation on a data item</p> Signup and view all the answers

    What does Unlock(X) do in transaction processing?

    <p>Allows other transactions to read the data item X</p> Signup and view all the answers

    In transaction processing, what happens when a data item is under an Exclusive lock?

    <p>It cannot be read or written by any other transaction until unlocked</p> Signup and view all the answers

    What is the purpose of a Shared lock in transaction processing?

    <p>Permitting multiple transactions to read a data item simultaneously</p> Signup and view all the answers

    What does an exclusive lock provide a transaction with?

    <p>Exclusive access to the item</p> Signup and view all the answers

    In the context of locking, what does it mean to upgrade a lock?

    <p>Changing from shared to exclusive lock</p> Signup and view all the answers

    Why is immediate unlocking after processing a data item considered incorrect?

    <p>Increases the likelihood of data inconsistency</p> Signup and view all the answers

    Which protocol requires all locking operations to precede the first unlock operation in a transaction?

    <p>2PL Protocol</p> Signup and view all the answers

    Why do the final results differ between serial and concurrent execution of transactions?

    <p>Inconsistent locking and unlocking procedures</p> Signup and view all the answers

    Which action does Transaction T2 take when data item A is already locked by Transaction T1 in exclusive mode?

    <p>T2 waits for T1 to unlock A before proceeding with its actions on A</p> Signup and view all the answers

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