What do you mean by time stamping protocol for concurrency controlling? Discuss multi version scheme of concurrency control.

Time stamping protocol for concurrency control is a method used in database systems to manage concurrent transactions and ensure that all data transactions occur in a specific order without violating the integrity of the database. This protocol assigns a unique timestamp to each transaction, which is used to determine the order in which transactions are to be executed.

The timestamp can be either the start time or the end time of the transaction. If the start time is used, it is known as the Thomas Write Rule, and if the end time is used, it is known as the Wait-Die and Wound-Wait Schemes.

The main advantage of this protocol is that it is a non-lock concurrency control mechanism, which means it does not require locking resources, which can lead to deadlocks.

On the other hand, the multi-version concurrency control (MVCC) scheme is another method used to handle concurrent transactions in a database system. This scheme creates a new version of a database object each time the object is written, allowing multiple versions of an object to exist simultaneously.

This allows for high concurrency and performance because read operations are never blocked. Each transaction sees a snapshot of the database at the start of the transaction. This snapshot remains consistent for the duration of the transaction.

The main advantage of MVCC is that it allows for high concurrency and performance because read operations are never blocked. However, it requires more storage space because it maintains multiple versions of each database object.