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Correct OPTION is (B) Immediate

Best EXPLANATION: If the database modifications occur while the transaction is still ACTIVE, the transaction is said to USE the immediate modification technique. Deferred modification has overhead whereas immediate modification doesn’t have any overhead.

Correct OPTION is (B) FUZZY

The best explanation: A fuzzy CHECKPOINT is a checkpoint where transactions are allowed to perform updates even while buffer blocks are being WRITTEN out.

Correct ANSWER is (a) True

To explain I would say: Using checkpoints reduces OVERHEAD because the search process is TIME consuming and searching for transactions does not TAKE place if we use checkpoints.

Right option is (c) Committed

To explain I would say: We say that a transaction has been committed when its commit LOG RECORD has been OUTPUT to stable storage. At that POINT, all the earlier RECORDS have already been output to stable storage.

Right ANSWER is (a) Deferred

Easiest explanation: If a transaction does not modify the database until it has committed it is SAID to use a deferred modification technique. Deferred modification has the overhead that transactions NEED to make local copies of all updated data items.

Right answer is (a) Transaction IDENTIFIER

For explanation I WOULD SAY: The unique identifier of the transaction that PERFORMED the write OPERATION is called as transaction identifier. This is a field in the update log record.

Right option is (d) All of the mentioned

For explanation: An update log record describes a single database write. It has FOUR FIELDS in it. The update log record has a TRANSACTION IDENTIFIER, data-item identifier, old value, NEW value.

The CORRECT option is (a) LOG

Explanation: The most widely used structure for RECORDING DATABASE modification is CALLED as a log. The log is a sequence of log records recording all the update activities in the database.

The correct answer is (b) Disk buffer

Best explanation: The area of MEMORY where blocks TEMPORARILY reside is CALLED as the disk buffer. The disk buffer is USED to STORE the buffer blocks which hold temporary data.

Correct CHOICE is (a) PHYSICAL blocks

Explanation: The blocks RESIDING on the disk are referred to as physical blocks. The blocks residing temporarily in the main memory are referred to as BUFFER blocks.

The correct option is (a) Blocks

For explanation: The DATABASE is partitioned into fixed length storage units called as blocks. Blocks are the units of DATA transfer and may contain several data ITEMS.

Correct answer is (b) False

The best I can explain: In CASE of total failure, the failure occurs sufficiently EARLY during the TRANSFER that the destination block remains intact. Thus there is no corruption of DATA at the destination.

Right ANSWER is (d) None of the mentioned

Best explanation: Volatile STORAGE, non-volatile storage and stable storage are three DIFFERENT classifications of storage. Volatile storage is the least secure whereas stable storage is the most secure AMONG them.

The correct answer is (c) Fail-STOP assumption

Explanation: The assumption that the hardware ERRORS bring the system to a halt is called as fail-stop assumption. Well-designed SYSTEMS have numerous internal CHECKS that bring a system to a halt whenever there is an error. HENCE, the fail stop assumption is a reasonable one.

Correct choice is (b) SYSTEM error

Explanation: If a system has ENTERED and undesirable state DUE to which it is unable to CONTINUE with normal execution, it is called as a system error. The transaction however can be re-executed at a LATER time.

The correct answer is (a) Logical error

To elaborate: If the transaction can no LONGER continue with its NORMAL EXECUTION because of some internal condition, it is called as a logical error such as bad input, data not FOUND, OVERFLOW or resource limit exceeded.

Correct answer is (c) More than one of the mentioned

For explanation: Logical ERRORS and system errors are the two types of errors that can GENERALLY cause TRANSACTION FAILURES.