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Exam 10: Transaction Management and Concurrency Control

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Question 31

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In the optimistic approach, during the phase, a transaction scans the database, executes the needed computations, and makes the updates to a private copy of the database values.

A) read
B) validation
C) write
D) shared

E) A) and B)
F) None of the above

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Question 32

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A(n) condition occurs when two or more transactions wait for each other to unlock data.

A) deadlock
B) exclusive lock
C) binary lock
D) two-phase lock

E) A) and B)
F) B) and C)

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Question 33

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can take place at any of the following levels: database, table, page, row, or field.

The serializable isolation level is the least restrictive level defined by the ANSI SQL standard.

A growing phase in a two-phase lock is when a transaction acquires all the required locks without locking any data.

A shared lock produces no conflict as long as all the concurrent transactions are read-write only.

A occurs when two or more transactions wait for each other to unlock data.

If T1 has not unlocked data item Y, T2 cannot begin; if T2 has not unlocked data item X, T1 cannot continue. Consequently, T1 and T2 each wait for the other to unlock the required data item. Such a deadlock is also known as a(n) _____.

The interleaves the execution of database operations to ensure serializability.

In the optimistic approach, during the phase, changes are permanently applied to the database.

Most real-world database transactions are formed by only one database request.

The occurs when two concurrent transactions, T1 and T2, are updating the same data element and one of the updates is lost.

What are the three basic techniques to control deadlocks?

control is important because the simultaneous execution of transactions over a shared database can create several data integrity and consistency problems.

Most multiuser automatically initiate and enforce locking procedures, where all locking information is managed by the lock manager.

occurs when a transaction accesses data before and after one or more other transactions finish working with such data.

The multiuser DBMS must implement controls to ensure serializability and isolation of transactions, in addition to atomicity and durability, in order to guard the database's consistency and integrity.

A(n) lock exists when concurrent transactions are granted read access on the basis of a common lock.

-level locks are less restrictive than database-level locks, but they create traffic jams when many transactions are waiting to access the same table.

Incomplete or improper transactions can have a devastating effect on database integrity.