Exam 13: Managing Transactions and Concurrency

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

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

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

A ____ lock locks the entire diskpage.

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.

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

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

The ANSI has defined standards that govern SQL database transactions. Transaction support is provided by two SQL statements: ____ and ROLLBACK.

The implicit beginning of a transaction is ____.

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.

The scheduler establishes the order in which the operations within concurrent transactions are executed.

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

An optimistic approach is based on the assumption that the majority of the database operations do not conflict.

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

A(n) ____ lock has only two stages (0 and 1).

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 ROLLBACK?

A ____ lock locks the entire table preventing access to any row by a transaction while another transaction is using the table.

A(n) ____ phase in a two-phase lock is when a transaction releases all locks and cannot obtain any new lock.

The ____________________ interleaves the execution of database operations to ensure serializability.