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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

Answer: A) Lossless Decomposition

Explanation:

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

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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

Answer: B) BCNF

Explanation:

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

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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

Answer: D) BCNF

Explanation:

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

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

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

Answer: B) F+

Explanation:

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

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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+

Answer: A) F

Explanation:

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

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

  1. Dependency
  2. Interdependency
  3. Intradependency
  4. Independency

Answer: A) Dependency

Explanation:

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

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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

Answer: D) 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.

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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

Answer: C) Ri-α

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.

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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

Answer: A) α+ - α

Explanation:

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

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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.

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

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

Answer: B) Big

Explanation:

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

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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

Answer: C) Over-normalize

Explanation:

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

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

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

Answer: B) Multi-valued

Explanation:

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

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14. ____ dependencies are the focus of BCNF.

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

Answer: B) Functional

Explanation:

Functional dependencies are the focus of BCNF.

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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

Answer: A) Multivalued

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.

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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

Answer: B) Functional

Explanation:

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

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

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

Answer: A) Multivalued

Explanation:

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

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18. ___ is another name for multivalued dependency.

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

Answer: A) Tuple-generating dependency

Explanation:

Tuple-generating dependency is another name for multivalued dependency.

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19. Functional dependencies are often called ___.

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

Answer: B) Equality-generating dependency

Explanation:

Functional dependencies are often called equality-generating dependencies.

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

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

Answer: A) 3NF

Explanation:

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

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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

Answer: B) Lossless

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.

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

  1. Dependency
  2. Interdependency
  3. Intradependency
  4. None

Answer: A) Dependency

Explanation:

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

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

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

Answer: C) Synthesis

Explanation:

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

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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

Answer: B) Normal

Explanation:

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

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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

Answer: D) 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.

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

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

Answer: D) Alternate

Explanation:

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

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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

Answer: C) Third

Explanation:

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

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