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Exam 10: Transaction Management and Concurrency Control

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Question 1

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One of the three most common data integrity and consistency problems is .

A) lost updates
B) disk failures
C) user errors
D) deadlocks

E) All of the above
F) B) and C)

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Question 2

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Uniqueness ensures that no equal time stamp values can exist, and ensures that time stamp values always increase.

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Question 3

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In a heavily used database management system (DBMS), the prevention and detection of constitutes an important DBMS function.

As a rule, a(n) must unlock the object after its termination.

The manager is responsible for assigning and policing the locks used by the transactions.

A scheduler facilitates data isolation to ensure that two transactions do not update the same data element at the same time.

To ensure consistency of the database, every transaction must begin with the database in an unstable state.

A(n) occurs when a transaction executes a query at time t1, and then it runs the same query at time t2, yielding additional rows that satisfy the query.

The isolation level ensures that queries return consistent results.

Time stamping demands a lot of system resources because many transactions might have to be stopped, rescheduled, and stamped.

are required to prevent another transaction from reading inconsistent data.

A field-level lock allows concurrent transactions to access the same row, as long as they require the use of different fields within that row.

What are database checkpoints?

The implicit beginning of a transaction is .

How do transaction recovery procedures use the deferred-write and write-through techniques to recover transactions?

The phenomenon of uncommitted data occurs when two transactions are executed concurrently and the first transaction is rolled back after the second transaction has already accessed the uncommitted data-thus violating the isolation property of transactions.

What is a rule that applies to the two-phase locking protocol?

To determine the appropriate order of the operations, the scheduler bases its actions on concurrency control algorithms, such as or time stamping methods.

In the wait/die scheme,:

Atomicity indicates the permanence of the database's consistent state.