# DBMS Decomposition Algorithms MCQs

DBMS Decomposition Algorithms MCQs: This section contains multiple-choice questions and answers on Decomposition Algorithms in DBMS.
Submitted by Anushree Goswami, on April 28, 2022

1. This method of decomposition focuses on ___ while preserving dependencies.

1. Lossless Decomposition
2. Loss Decomposition
3. Less Decomposition
4. Lossfull Decomposition

Explanation:

This method of decomposition focuses on lossless decomposition while preserving dependencies.

2. You should test the Boyce-Codd Normal Form of the relationship before applying the ___ decomposition algorithm.

1. 3NF
2. BCNF
3. 4NF
4. 2NF

Explanation:

You should test the Boyce-Codd Normal Form of the relationship before applying the BCNF decomposition algorithm.

3. The given relation can be decomposed further to create ___ relations if the test finds that it is not in BCNF.

1. 3NF
2. 4NF
3. 5NF
4. BCNF

Explanation:

The given relation can be decomposed further to create BCNF relations if the test finds that it is not in BCNF.

4. If R is found in BCNF, all dependencies in ___ need not be tested.

1. F
2. F+
3. R
4. R+

Explanation:

If R is found in BCNF, all dependencies in F+ need not be tested.

5. For the BCNF test, it is only necessary to determine and check the dependencies of the provided dependency set ___.

1. F
2. F+
3. S
4. S+

Explanation:

For the BCNF test, it is only necessary to determine and check the dependencies of the provided dependency set F.

6. The F+ dependencies will not violate BCNF if no ___ in F violates it.

1. Dependency
2. Interdependency
4. Independency

Explanation:

The F+ dependencies will not violate BCNF if no dependency in F violates it.

7. A BCNF decomposition algorithm is used when a given relationship R is split into a series of relatedness relations R1, R2, ... , Rn due to its absence from the ___.

1. 2NF
2. 3NF
3. 4NF
4. BCNF

Explanation:

A BCNF decomposition algorithm is used when a given relationship R is split into a series of relatedness relations R1, R2,..., Rn due to its absence from the BCNF.

8. We need to verify that α+ (an attribute closure of α under F) either includes all the attributes of the relation Ri or no attributes of ___, for every subset α of attributes in the relation Ri.

1. α
2. Ri+α
3. Ri-α
4. Ri

Explanation:

We need to verify that α+ (an attribute closure of α under F) either includes all the attributes of the relation Ri or no attributes of Ri-α, for every subset α of attributes in the relation Ri.

9. When an attribute α in Ri violates the algorithmic condition, consider the functional dependency (___) ꓵ Ri in such cases.

1. α+ - α
2. α+ + α
3. α+ * α
4. α+ / α

Explanation:

When an attribute α in Ri violates the algorithmic condition, consider the functional dependency (α+ - α) ꓵ Ri in such cases.

10. Which of the following is TRUE about BCNF Decomposition Algorithm?

1. To decompose a given relation R, this algorithm consists of decomposing it into several decomposers.
2. The decomposition of the relation R is performed by using dependencies that show the violation of BCNF.
3. In addition to producing decomposers for relation R in BCNF, such an algorithm also produces lossless decompositions.
4. All of the above

Answer: D) All of the above

Explanation:

In case of BCNF Decomposition Algorithm -

1. To decompose a given relation R, this algorithm consists of decomposing it into several decomposers.
2. The decomposition of the relation R is performed by using dependencies that show the violation of BCNF.
3. In addition to producing decomposers for relation R in BCNF, such an algorithm also produces lossless decompositions.

11. When the initial relation schema R is ___, the BCNF decomposition algorithm takes exponentially more time.

1. Small
2. Big
3. Little
4. None

Explanation:

When the initial relation schema R is big, the BCNF decomposition algorithm takes exponentially more time.

12. Due to its unnecessarily decomposable nature, this algorithm will ___ the given relation R.

1. Normalize
2. Under-normalize
3. Over-normalize
4. All of the above

Explanation:

Due to its unnecessarily decomposable nature, this algorithm will over-normalize the given relation R.

13. ___ are the basis of the fourth normal form.

1. Functional
2. Multi-valued
3. Single-valued
4. None

Explanation:

Multi-valued dependencies are the basis of the fourth normal form.

14. ____ dependencies are the focus of BCNF.

1. Multi-valued
2. Functional
3. Both a and b
4. None

Explanation:

Functional dependencies are the focus of BCNF.

15. With the help of _____ dependencies, we can reduce some instances where data is repeated, which would not make sense if we looked at it from a functional dependency perspective.

1. Multivalued
2. Functional
3. Both A and B
4. All of the above

Explanation:

With the help of multivalued dependencies, we can reduce some instances where data is repeated, which would not make sense if we looked at it from a functional dependency perspective.

16. Unlike multivalued dependencies, ____ dependencies do not expel certain tuples from being members of a relationship.

1. Multivalued
2. Functional
3. Singlevalued
4. All of the above

Explanation:

Unlike multivalued dependencies, functional dependencies do not expel certain tuples from being members of a relationship.

17. A dependent ___ set does not exclude or expel any tuples.

1. Multivalued
2. Singlevalued
3. Functional
4. None

Explanation:

A dependent multivalued set does not exclude or expel any tuples.

18. ___ is another name for multivalued dependency.

1. Tuple-generating dependency
2. Tuple-generating interdependency
4. None

Explanation:

Tuple-generating dependency is another name for multivalued dependency.

19. Functional dependencies are often called ___.

1. Tuple-generating dependency
2. Equality-generating dependency
3. Both A and B
4. None of the above

Explanation:

Functional dependencies are often called equality-generating dependencies.

20. In the canonical cover, each dependency is explicitly defined through the decomposition algorithm for ____.

1. 3NF
2. 4NF
3. 5NF
4. BCNF

Explanation:

In the canonical cover, each dependency is explicitly defined through the decomposition algorithm for 3NF.

21. By ensuring that at least one schema contains a candidate key for the one being decomposed, the generated decomposition is guaranteed to be ______.

1. Loss
2. Lossless
3. Lossfull
4. Less

Explanation:

By ensuring that at least one schema contains a candidate key for the one being decomposed, the generated decomposition is guaranteed to be lossless.

22. While maintaining the dependency as well as decomposing the relation R losslessly, the algorithm also preserves the dependencies.

1. Dependency
2. Interdependency
4. None

Explanation:

While maintaining the dependency as well as decomposing the relation R losslessly, the algorithm also preserves the dependencies.

23. 3NF algorithms can also be referred to as 3NF ____ algorithms.

1. Syntax
2. Seasonal
3. Synthesis
4. Synthetic

Explanation:

3NF algorithms can also be referred to as 3NF synthesis algorithms.

24. By creating a dependency set, the ____ form adds one schema at a time, rather than repeatedly decomposing the initial schema.

1. Abnormal
2. Normal
3. Simple
4. Complex

Explanation:

By creating a dependency set, the normal form adds one schema at a time, rather than repeatedly decomposing the initial schema.

25. A set of functional dependencies can have ___ canonical cover, so the result of decomposing the algorithm is not unique.

1. One
2. Two
3. Three
4. More than one

Explanation:

A set of functional dependencies can have more than one canonical cover, so the result of decomposing the algorithm is not unique.

26. When the algorithm considers the dependencies in Fc in an ____ order, the result may differ.

1. Random
2. Consecutive
3. Simultaneous
4. Alternate

Explanation:

When the algorithm considers the dependencies in Fc in an alternate order, the result may differ.

27. It is possible to decompose a relation if an existing relation already exists in the ___ normal form.

1. First
2. Second
3. Third
4. Fourth

Explanation:

It is possible to decompose a relation if an existing relation already exists in the third normal form.

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