db test 10

All transactions must display ____.

During the ____ phase, a transaction scans the database, executes the needed computations, and makes the updates to a private copy of the database values.

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

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

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

As long as two transactions, T1 and T2, access ____ data, there is no conflict, and the order of execution is irrelevant to the final outcome.

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

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

The transaction recovery write-ahead-log protocol ensures that transaction logs are always written before any database data are actually updated.

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.

____ requires that all operations of a transaction be completed

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

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.

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

Durability requires that all portions of the transaction must be treated as a single, logical unit of work in which all operations are applied and completed to produce a consistent database.

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

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

____ are rules that applies to the two-phase locking protocol.

The implicit beginning of a transaction is ____.

When using an optimistic approach, during the write phase the transaction is validated to ensure that the changes made will not affect the integrity and consistency of the database.

A diskpage, or page, is the equivalent of a ____.

A(n) ____ specifically reserves access to the transaction that locked the object.

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

The DBMS guarantees that the semantic meaning of a transaction truly represents the real-world event.

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.

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.

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

A consistent database is ____.

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

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.

A ____ lock allows concurrent transactions to access different rows of the same table.

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

In a page-level lock, the DBMS will lock an entire diskpage

A ____ lock locks the entire diskpage.

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

During the ____ phase, changes are permanently applied to the database.

A transaction is a ____ unit of work that must be either entirely completed or aborted.

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

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

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

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

ANSI defines four events that signal the end of a transaction. Of the following events ____ is defined by ANSI as being equivalent to a ROLLBACK.

When you When you read from or update a database, you create a transaction.

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

Lock ____ indicates the level of lock use.

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

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

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

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