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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.
- Lossless Decomposition
- Loss Decomposition
- Less Decomposition
- 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.
- 3NF
- BCNF
- 4NF
- 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.
- 3NF
- 4NF
- 5NF
- 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.
- F
- F+
- R
- 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 ___.
- F
- F+
- S
- 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.
- Dependency
- Interdependency
- Intradependency
- 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 ___.
- 2NF
- 3NF
- 4NF
- 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.
- α
- Ri+α
- Ri-α
- 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.
- α+ - α
- α+ + α
- α+ * α
- 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?
- To decompose a given relation R, this algorithm consists of decomposing it into several decomposers.
- The decomposition of the relation R is performed by using dependencies that show the violation of BCNF.
- In addition to producing decomposers for relation R in BCNF, such an algorithm also produces lossless decompositions.
- All of the above
Answer: D) All of the above
Explanation:
In case of BCNF Decomposition Algorithm -
- To decompose a given relation R, this algorithm consists of decomposing it into several decomposers.
- The decomposition of the relation R is performed by using dependencies that show the violation of BCNF.
- 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.
- Small
- Big
- Little
- 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.
- Normalize
- Under-normalize
- Over-normalize
- 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.
- Functional
- Multi-valued
- Single-valued
- 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.
- Multi-valued
- Functional
- Both a and b
- 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.
- Multivalued
- Functional
- Both A and B
- 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.
- Multivalued
- Functional
- Singlevalued
- 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.
- Multivalued
- Singlevalued
- Functional
- 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.
- Tuple-generating dependency
- Tuple-generating interdependency
- Tuple-generating intradependency
- 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 ___.
- Tuple-generating dependency
- Equality-generating dependency
- Both A and B
- 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 ____.
- 3NF
- 4NF
- 5NF
- 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 ______.
- Loss
- Lossless
- Lossfull
- 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.
- Dependency
- Interdependency
- Intradependency
- 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.
- Syntax
- Seasonal
- Synthesis
- 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.
- Abnormal
- Normal
- Simple
- 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.
- One
- Two
- Three
- 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.
- Random
- Consecutive
- Simultaneous
- 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.
- First
- Second
- Third
- 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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