What is two-phase locking technique?

Two-Phase Locking (2PL) is a concurrency control method which divides the execution phase of a transaction into three parts. It ensures conflict serializable schedules. If read and write operations introduce the first unlock operation in the transaction, then it is said to be Two-Phase Locking Protocol.

What do you mean by two phase locking protocol can this protocol solve the deadlock explain with suitable example also?

Deadlock in 2-PL –

Say we have two transactions T1 and T2. Drawing the precedence graph, you may detect the loop. So Deadlock is also possible in 2-PL. Two-phase locking may also limit the amount of concurrency that occurs in a schedule because a Transaction may not be able to release an item after it has used it.

What is a locking protocol?

Locking protocols are used in database management systems as a means of concurrency control. Multiple transactions may request a lock on a data item simultaneously. Hence, we require a mechanism to manage the locking requests made by transactions. Such a mechanism is called as Lock Manager.

What are some variations of the two-phase locking protocol?

There are three categories:
Strict 2-PL.Rigorous 2-PL.Conservative 2-PL.

What is two-phase locking and how we can prevent deadlock?

Two phase locking prevents deadlock from occuring in distributed systems by releasing all the resources it has acquired, if it is not possible to obtain all the resources required without waiting for another process to finish using a lock.

Which among the following 2 phase locking protocols is a deadlock free?

2pl is a deadlock free protocol but it is difficult to use in practice.

What is the difference between two-phase locking and strict two-phase locking in transactions?

1. In Conservative 2-PL, A transaction has to acquire locks on all the data items it requires before the transaction begins it execution. In Strict 2-PL, A transaction can acquire locks on data items whenever it requires (only in growing phase) during its execution. 2.

What is 2 phase locking protocol is 2 phase locking ensure freedom from deadlock?

Rigorous two phase locking protocol

A transaction cannot release any lock either shared or exclusive until it commits. The 2PL protocol guarantees serializability, but cannot guarantee that deadlock will not happen.

What is a lock explain binary and read/write locks What is two-phase locking explain different variations of two-phase locking?

Locks are of two kinds − Binary Locks − A lock on a data item can be in two states; it is either locked or unlocked. Shared/exclusive − This type of locking mechanism differentiates the locks based on their uses. If a lock is acquired on a data item to perform a write operation, it is an exclusive lock.