Explain dynamic two-phase locking, Database Management System

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Explain Dynamic Two-Phase Locking

Here a transaction locks a data item instantly earlier than any operation is applied on the data item.  After finishing all the operations on all the data items, it releases all the locks. An instance of dynamic 2PL is as following 

X(X)

Read (X)

X=X+M

Write (X)

X (Y)

Read (Y)

Y=Y+N

Write Y

Unlock (Y)

Unlock (X)


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