Multiple choices questions in DBMS, Is timestamp ordering protocol free from deadlock? Why do we say that the timestamp ordering protocol is free from deadlock? Concurrency control in DBMS

DBMS MCQ - Timestamp ordering protocol

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1. Timestamp ordering protocol is said to be free from deadlock because of this reason.

a) It is cascade free

b) It guarantees serializability

c) No transaction is made to wait

d) Every write operation updates the W-timestamp of the data item

Answer: (c) No transaction is made to wait

In timestamp ordering protocol, a transaction is either permitted to execute the operation or rolled back. No transaction is made to wait for some other transaction. A transaction is permitted to execute in all the following cases and rolled back otherwise;

A transaction T that tries to execute read(Q) operation will be permitted if and only if the timestamp(T) >= W-timestamp(Q). That is, T is permitted to execute if it is started after a successful write on Q by some transactions.

A transaction T that tries to execute write(Q) operation will be permitted if the timestamp(T) is greater than both the R-timestamp(Q) and W-timestamp(Q). That is, T is permitted to write a data item which was read/write by older transactions.

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