Question

Discuss the advantages and disadvantages of 2PL and Strick 2PL protocols. Beside the locking protocol, what is the additional requirement to ensure the transactional isolation property?

Answer 1

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Two-Phase Locking Protocol

The utilization of locks has helped us to make slick and clean simultaneous timetable.
The Two Phase Locking Protocol characterizes the principles of how to get the locks on an information thing and how to deliver the locks.

Two phase locking(2PL) is aconcurrency controlmethod that guaranteesserializability.
The protocol utilizeslocks, applied by an exchange on information, which may obstruct (stop) different exchanges from getting to a similar information during the exchange's life.
The Two Phase Locking Protocol accepts that an exchange must be in one of two phases.Phase 1 - Developing Phase

In this phase the exchange can just secure locks, yet can't deliver any lock.

The exchange enters the developing phase when it procures the firstlock it needs.

Starting now and into the foreseeable future it has no choice except for to continue gaining all the locks it would require.

It can't deliver any lock at this phase regardless of whether it has completed the process of working with a bolted information thing.

Eventually the exchange arrives at a point where all the lock it might require has been gained. This point is called Lock Point.Phase 2 - Contracting Phase

After Lock Point has been reached, the exchange enters the contracting phase.

In this phase the exchange can just delivery locks, yet can't get any new lock.

The exchange enters the contracting phase when it delivers the main lock in the wake of intersection the Lock Point.

Starting now and into the foreseeable future it has no alternative except for to continue delivering all the procured locks.

At first the exchange is in developing phase, that is the exchange gains bolts varying.

When the exchange discharges lock, it enters the contracting phase and no more lock solicitation might be given.

Updating of lock is unimaginable in contracting phase, however it is conceivable in developing phase.

The two phase locking protocol guarantees serializability.

There are two unique adaptations of the Two Phase Locking Protocol. 1)Strict Two Phase Locking Protocol 2)Rigorous Two Phase Locking Protocol.

Strict Two Phase Locking Protocol

In this protocol, an exchange may deliver all the mutual locks after the Lock Point has been reached, yet it can't deliver any of the restrictive locks until the exchange commitsor prematurely ends.

This guarantee that any information composed by an uncertain exchange are secured elite mode until the exchange submits and keeping other exchange from perusing that information .This protocol takes care of filthy read issue.

Rigorous Two Phase Locking Protocol

In Rigorous Two Phase Locking Protocol, an exchange isn't permitted to deliver any lock (either shared or selective) until it submits. This implies that until the exchange submits, other exchange may get a common lock on an information thing on which the uncertain exchange has a mutual lock; yet can't procure any lock on an information thing on which the uncertain exchange has a select lock

Preferences

Recuperation is simple.

Disservices

Simultaneousness is decreased