Fragmentation in Distributed Database - Quiz

Database System Architectures - Quiz

1. What are the advantages of Replication of data in Distributed database?

Avaliability, Parallelism, Increased data transfer
Availability, Parallelism, Reduced data transfer
Availability, Increased parallelism, Cost of updates
All of the above

2. A fragmentation technique wherein every tuple of a table is assigned to one or more fragments as a result of fragmentation is called ________________ .

Vertical Fragmentation
Horizontal Fragmentation
Hybrid Fragmentation
None of the above

Assume a relation EMP as given below:

                EMP(EmpNo, EName, Job, Sal, Department)

Furthermore, assume that there are two applications which are accessing the above mentioned table. One application typically retrieves information about employees who earn more than Rs5.000, the other application typically manages information about 'clerks' (job). Also, assume that there are employees with other designations and different salaries stored in EMP. With this information, answer the questions 3 to 6.

3. Which of the following are the simple predicates which can be directly extracted from the given applications?

{Job = clerk, Salary>5000}
{Job = clerk, Salary<5000}
{Job = Manager, Salary>5000}
{Job = Manager, Salary<5000}

4. How many valid minterm predicates we can derive for the above said problem?

4
5
3
2

5. Assume that the departments are 'Finance', 'Production', and 'Design'. If there is one more application which accesses the informatoin frequently based on the 'Finance' department, what would be the number of valid minterm fragments?

5
6
7
8

6. If by mistake, I miss one of the valid minterm fragments. What would be the effect of that in fragmentation?

Causes skew
Reconstruction of EMP will be unsuccessful
Slows down the database access
None

7. Which of the following failures are unique to distributed database systems?

Failure of a site
Loss of messages
Network Partition
All the above

8. For the given set of simple predicates Pr, how many min-term predicates we can derive (including invalid ones). Pr = {Branch = “Vellore”, Branch = “Chennai”, Salary <=20000, Salary > 20000} Assumptions: Consider there are five different branches.

4
8
16
32

9. In a distributed database application, if we have very many number of read only queries than update queries then ______________ allocation technique is advantageous.

Hybrid Fragmentation
Horizontal Fragmentation
Replication
Vertical Fragmentation

10. Which of the following would be the advantage of Database Fragmentation?

Most of the operations are local to any sites
Reduced Network Traffic
Parallel processing
All the above

Score =

Correct answers:

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Database Management Systems - Relational Algebra quiz

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Let us use the following relations R and S to answer the questions 1 – 10s;
A B 3 3 6 4 2 3 3 5 3 6	B C D 5 1 6 3 3 5 4 3 1
1. Compute R ⋈ S. Which of the following records will be in the result? Assume each record has the schema (A, B, C, D).
(a) (3, 3, 1, 6)	(b) (6, 4, 4, 1)
(c) (2, 3, 3, 5)	(d) (3, 5, 3, 1)
2. Compute R ⋈R.A<S.C S. [this is theta join]. Which of the following records will be in the result? Assume each record has the schema (A, B, C, D).
(a) (2, 3, 3, 5)	(b) (6, 4, 4, 1)
(c) (6, 4, 3, 1)	(d) (3, 5, 1, 6)
3. Compute R ⋈R.B < S.D AND R.A<S.C S. [this is theta join]. Which of the following records will be in the result? Assume each record has the schema (A, B, C, D).
(a) (3, 3, 3, 5)	(b) (6, 4, 3, 1)
(c) (2, 3, 3, 5)	(d) (3, 5, 1, 6)
4. Compute π C, D (S). Which of the following records will be in the result?
(a) (5, 1)	(b) (4, 3)
(c) (3, 3)	(d) (3, 5)
5. Compute π B, C (R ⋈ S). Which of the following records will be in the result?
(a) (6, 4)	(b) (4, 3)
(c) (5, 1)	(d) (5, 3)
6. Compute π B (R) - π B (S). Which of the following records will be in the result?
(a) (6)	(b) (4)
(c) (1)	(d) (5)
7. Compute π B (R) ∩ π B (S). Which of the following records will be in the result?
(a) (6)	(b) (1)
(c) (2)	(d) (5)
8. Compute R ⋈ S. Which of the following records will be in the result? Assume each record has the schema (A, B, C, D).
(a) (3, 3, 1, 6)	(b) (6, 4, 4, 1)
(c) (3, 5, 1, 6)	(d) (3, 5, 3, 1)
9. Compute π B (R) U π B (S). Which of the following records will be in the result?
(a) (6)	(b) (1)
(c) (2)	(d) (5)
10. Assume a relation R(A, B) with n unique records, and a relation S(B, C) with m unique records. When you compute the natural join between R and S you shall get r records as the result. Which of the following assumptions are correct in terms of (n, m, r)?
(a) (5, 4, 25)	(b) (2, 3, 8)
(c) (3, 3, 10)	(d) (2, 3, 6)

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Database management systems - Normalization and normal forms quiz

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Normalization QUIZ

1. Assume that a relation R has the following properties. What is the normal form of R?             No multi-valued attributes             No partial key dependencies
(a) First Normal Form	(b) Second Normal Form
(c) Third Normal Form	(d) Boyce-Codd Normal Form
2. Assume that a relation R has the following properties. What is the normal form of R?             Has no partial key dependencies             Has multi-valued attributes
(a) First Normal Form	(b) Second Normal Form
(c) Third Normal Form	(d) None of the above
3. All functional dependencies must _________
(a) have attributes of the same table	(b) have a single attribute on its LHS
(c) have a single attribute on its RHS	(d) All of the above
4. Which one of the following is always a single-valued attribute?
(a) a person’s phone number	(b) a person’s address
(c) a person’s age	(d) a person’s car
Let R (A, B, C, D, E, F) be a relation with the functional dependencies A → B, A → C, CD → E, CD → F, B → E. Use this information to answer questions 5, 6, and 7.
5. Which of the following does not hold on R?
(a) A → E	(b) CD → EF
(c) AD → F	(d) B → CD
6. Which of the following is holding on R?
(a) A → C	(b) B → A
(c) CD → A	(d) C → D
7. Which of the following does not hold on R?
(a) BC → D	(b) AD → B
(c) BC → E	(d) ACD → BEF
8. A functional dependency that exist between two non-key attributes is called _____
(a) Non-transitive dependency	(b) Transitive dependency
(c) Partial transitive dependency	(d) None of the above
9. Assume that a relation R has the following properties. What is the normal form of R?             Has no multi-valued attributes             Has no partial key dependencies             Has attributes with atomic domains             Has transitive dependencies
(a) 1NF & 2NF	(b) 1NF, 2NF, & 3NF
(c) 1NF & 3NF	(d) BCNF
10. Assume a relation R with the following 3 attributes; one attribute as primary key, one attribute as foreign key and one non-key attribute. Also, none of them is multi-valued attribute. What is the maximum normal form R can be in?
(a) 1NF	(b) 2NF
(c) 3NF	(d) BCNF

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