Exam 9: Managing Multiuser Databases

A durable transaction is one for which all committed changes are permanent.

A dirty read happens when one transaction reads a changed record that has not been committed to the database.

All commercial DBMS products use some version of "username and password" as part of their security features.

Which of the following is not true about two-phased locking?

With optimistic locking,the assumption is made that no conflict will occur.

In two-phase locking,all locks are obtained during the growing phase.

Requiring all application programs to lock resources in the same order is a technique for preventing what problem?

Processing rights may be implemented at the DBMS level.

Which of the following is not true of DBMS security features?

Locks that are placed assuming that a conflict will not occur are called ________.

Explain the importance of documenting changes in database structure.

The task of diagnosing errors due to changes in the database structure is eased by ________.

Which of the following is not true of data repositories?

A standby data repository is one which requires a person to generate the metadata and place it in the repository.

Locks placed by a command issued to the DBMS from the application program are called explicit locks.

Requiring all application programs to lock resources in the same order is one way of preventing a deadlock condition.

Which type of data repository is composed of metadata that is created automatically as the system components are created?

A lock placed automatically by the DBMS is called a(n)________ lock.

Briefly explain the strategy of two-phased locking.

Explicit locks are locks that are placed automatically by the DBMS.