Exam 9: Managing Multiuser Databases

Which of the following is allowed by "Repeatable Read Isolation"?

Locks placed automatically by the DBMS are called implicit locks.

With pessimistic locking,the assumption is made that a conflict will occur.

A database save is used to mark the end of a transaction.

The DBA has to find a balance between the conflicting goals of maximizing availability of the database to users and protecting the database.

The DBA should periodically analyze run-time statistics of database performance to help manage the DBMS.

In general,the overall responsibility of the DBA is to facilitate the development and use of the database system.

Briefly define the four isolation levels and the problems they prevent.

Nonrepeatable reads occur when a transaction rereads data it has previously read and finds modifications or deletions caused by a committed transaction.

Concurrency control measures are taken to ensure that one user's work has absolutely no influence on another user's work.

Reprocessing is normally the most convenient method for recovery after a system failure.

An active data repository is one in which the metadata is automatically created as the system components are created.

A series of actions to be taken on the database such that either all actions are completed successfully,or none of them can be completed,is known as a ________.

Explain the process of using optimistic locking.

Distinguish between the four cursor types.

A dynamic cursor saves primary key values when the cursor is opened and retrieves the values for each row as the application program accesses it.

Copies of each database record or page after it was changed by a transaction that are saved for use in database recovery are called ghost images.

Which are more commonly used: implicit or explicit locks? Why?

When a transaction rereads data that has been changed and finds changes due to committed transactions,this is known as a ________.

Which of the following would not be contained in a transaction log?