Distributed DBMS

Question 1

What is a distributed DBMS?

Answer 1

A collection of data with different parts under the control of separate DBMS running on different systems.

Question 2

Give disadvantages of heterogenous distributed database.

Answer 2

Difference in Schema is a major problem for query processing.
Difference in software is a major problem for transaction processing.
Sites may not be aware of each other and may provide limited facilities for cooperation in transaction processing.

Question 3

What are two types of data fragmentation?

Answer 3

Horizontal

Vertical

Question 4

What is horizontal fragmentation?

Answer 4

When each Tuple of r is assigned to one or more fragments.

Question 5

What is vertical fragmentation?

Answer 5

When the Schema for relation r is split into several smaller schemes.

Question 6

Give advantages of horizontal fragmentation.

Answer 6

Allows parallel processing on fragments of a relation.

Allows a relation to be split so that tuples are located where they are most frequently accessed.

Question 7

Give advantages of vertical fragmentation.

Answer 7

Allows tuples to be split.
Tuple id attribute allows efficient joining of vertical fragments.
Allows parallel processing on a relation.