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Exam 10: Transaction Management and Concurrency Control

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Question 1

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What are the three basic techniques to control deadlocks?

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Deadlock prevention.A transaction reques...

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Question 2

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

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

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

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

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

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

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.

The ____ approach to scheduling concurrent transactions assigns a global unique stamp to each transaction.

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

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.

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

When using an optimistic approach,a transaction reads the database,executes the needed computations,and makes the updates to a private copy of the database values.

Explain the transaction log.What is its function?

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

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.

The DBMS keeps several copies of ____________________ to ensure that a disk physical failure will not impair the DBMS's ability to recover data.

The information stored in the ____ is used by the DBMS for a recovery requirement triggered by a ROLLBACK statement,a program's abnormal termination,or a system failure such as a network discrepancy or a disk crash.

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?

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