UNIT III-TRANSACTION PROCESSING AND CONCURRENCY CONTROL PART A-2 MARKS 1. What are the ACID properties? To ensure the integrity of data (atomicity, consistency, isolation, durability) is a set of properties that guarantee database transactions are processed reliably. What are the states of transaction? The states of transaction are Active Partially committed Failed Aborted Committed Terminated 3. Give the reasons for allowing concurrency? If the transactions run serially, a short transaction may have to wait for a preceding long transaction to complete, which can lead to unpredictable delays in running a transaction. So concurrent execution reduces the unpredictable delays in running transactions. Differentiate strict two locking protocol and rigorous two phase locking protocol. In strict two phase locking protocol all exclusive mode locks taken by a transaction is held until that transaction commits. Rigorous two phase locking protocol requires that all locks be held until the transaction commits. 5. Define deadlock? When each transaction T in a set of two or more transactions is waiting for some item that is locked by some other transaction T in the set. This situation is called as deadlock State the benefits of strict two phase locking. Two Phase locking protocol prevent deadlock. This protocol maintains the schedule which lock should be granted or not. Ensures Serializability.
UNIT III-TRANSACTION PROCESSING AND CONCURRENCY CONTROL PART A-2 MARKS 1. What are the ACID properties? To ensure the integrity of data (atomicity, consistency, isolation, durability) is a set of properties that guarantee database transactions are processed reliably. What are the states of transaction? The states of transaction are Active Partially committed Failed Aborted Committed Terminated 3. Give the reasons for allowing concurrency? If the transactions run serially, a short transaction may have to wait for a preceding long transaction to complete, which can lead to unpredictable delays in running a transaction. So concurrent execution reduces the unpredictable delays in running transactions. Differentiate strict two locking protocol and rigorous two phase locking protocol. In strict two phase locking protocol all exclusive mode locks taken by a transaction is held until that transaction commits. Rigorous two phase locking protocol requires that all locks be held until the transaction commits. 5. Define deadlock? When each transaction T in a set of two or more transactions is waiting for some item that is locked by some other transaction T in the set. This situation is called as deadlock State the benefits of strict two phase locking. Two Phase locking protocol prevent deadlock. This protocol maintains the schedule which lock should be granted or not. Ensures Serializability.
CS6302-III%20SEM.docx