Thursday, September 20, 2007

Serializability and Locking Schemes

Notes on Serializability and Locking Schemes -

When multiple Transaction run concurrently, DB consistency can be destroyed, despite the correctness of the each individual Transaction.

To prevent this we use ‘Concurrency-Control Schemes’

The various ‘Concurrency-Control Schemes’ are as:

- Lock-Based Protocols.

- Two-Phase Locking

- Graph-Based Locking (Skip)

- Timestamp-Based Protocol.

- Validation-Based Protocol.

- Multiple Granularity.

- Multiversion Schemes.

Concurrency-Control Schemes - Are used to ensure that the Concurrent Schedules are Serializable.

Serilaizable means - Assuring that a concurrent schedule will ensure consistency or not. i.e Assuring Serilizability.

Serializability can be ensured in two ways-

- Conflict Serializability

- A concurrent schedule is Conflict Serializable if it is conflict equivalent to a Serial Schedule

- View Serializability

- Leave it

Thanks & Regards,

Arun Manglick || Tech Lead

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