Explain the Static or conservative Two Phase Locking:
Static (or conservative) Two Phase Locking: In this type of scheme, all the data items are locked earlier than any operations on them and are released just only after the last operation carried out on any data item.
X(X)
X (Y)
Read (X)
Write (X)
Read (Y)
Y = Y+N
Write Y
Unlock (X)
Unlock (Y)
In static 2PL, requests from other transactions for data items locked by the previous transaction will be delayed without need, so causing a serious impact on system performance.