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Exam 13: Managing Transactions and Concurrency

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Question 21

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Database transaction ____________________ restores a database from an inconsistent state to a previously consistent state.

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Question 22

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ANSI defines four events that signal the end of a transaction. Of the following events, which is defined by ANSI as being equivalent to a COMMIT?

A) Five SQL statements are executed.
B) The end of a program is successfully reached.
C) The program is abnormally terminated.
D) The database is shut down for maintenance.

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

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Question 23

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The ____________________ rule states that only one transaction at a time can own an exclusive lock on the same object.

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

____ are required to prevent another transaction from reading inconsistent data.

How does a shared/exclusive lock schema increase the lock manager's overhead?

A single-user database system automatically ensures ____ of the database, because only one transaction is executed at a time.

What are database checkpoints?

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

Although the DBMS is designed to recover a database to a previous consistent state when an interruption prevents the completion of a required set of transactions, the transactions themselves are defined by the end user or programmer and must be semantically correct.

Serializability means that data used during the execution of a transaction cannot be used by a second transaction until the first one is completed.

The last step in the write-through technique recovery procedure is to identify the last checkpoint in the transaction log.

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

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

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

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

If a(n) ____________________ is issued before the termination of a transaction, the DBMS will restore the database only for that particular transaction, rather than for all transactions, in order to maintain the durability of the previous transactions.

A consistent database state is ____.

A ____ lock prevents the use of any tables in the database from one transaction while another transaction is being processed.

What are the three basic techniques to control deadlocks?