Exam 12: Distributed Databases

In a homogeneous distributed database environment,all users access the database through one ________.

A replicated database with snapshots is very manageable.

Which of the following is true of data replication?

A distributed DBMS uses a(n)________ to predict the execution time of alternative execution plans.

An integrated partition strategy is ________ to manage.

What is the difference between a local transaction and a global transaction?

Concurrency transparency allows each transaction to appear as if it were the only activity in a distributed database management system.

In a semijoin,all of the selected attributes from every selected row are transmitted to each site.

When separate copies of data are stored at each of two or more sites,it is called ________.

A distributed database may require more costly and complex software than a centralized database.

Replication should not be used if timely updates are important.

Location transparency is used to inform users of where data are located within the distributed database.

What business conditions encourage the use of distributed databases?

A(n)________ is a joining operation used with distributed databases in which only the joining attribute from one site is transmitted to the other site.

Horizontal partitioning offers increased efficiency because data are close to use areas.

In a distributed database,a transaction that requires reference to data at one or more nonlocal sites is called a ________ transaction.

What are the three different kinds of transparencies used in distributed database management systems?

A design goal for distributed databases that guarantees either all the actions or none of the actions in a transaction are committed is ________.

Snapshot replication is most appropriate for:

Users of distributed database systems always need to know the location of the data.