Transaction Locking Method Quiz

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

Lock (X), Write (X), Unlock (X)

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

A transaction is well-formed if it never locks a locked data item or tries to unlock an unlocked data item.

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

Read and Write

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

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

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

To enable write operations on the locked item by the transaction holding the lock. 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?

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

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

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

What does a shared lock allow in transaction processing?

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

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

Preventing any write operation on a data item Signup and view all the answers

What does Unlock(X) do in transaction processing?

Allows other transactions to read the data item X Signup and view all the answers

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

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

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

Permitting multiple transactions to read a data item simultaneously Signup and view all the answers

What does an exclusive lock provide a transaction with?

Exclusive access to the item Signup and view all the answers

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

Changing from shared to exclusive lock Signup and view all the answers

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

Increases the likelihood of data inconsistency Signup and view all the answers

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

2PL Protocol Signup and view all the answers

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

Inconsistent locking and unlocking procedures 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?

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