GATE CSE Databases PYQs & Answers

Questions 1–10 of 73. Imported answers require independent review unless marked reviewed.

In the context of DBMS, consider the two sets T and S given below.

T | S I: Logical schema | L: Views II: Physical schema | M: File organization and indexes III: External schema | N: Relations

Which one of the following is the correct match from T to S?

Your answerChoose one option.

I – L, II – M, III – N

I – M, II – L, III – N

I – N, II – M, III – L

I – N, II – L, III – M

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Consider concurrent execution of two transactions

and

in a DBMS, both of which access a data object

. For these two transactions to not conflict on

, which one of the following statements must be true?

Your answerChoose one option.

Both

and

only read

reads

and

writes

and

reads

Both

and

write

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Let

and

be the attributes of a relation in a relational schema. Let

indicate functional dependency in the context of a relational database, where

Which of the following options is/are always true?

Your answerSelect all correct options. You can choose more than one.

and

, then

and

, then

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In the context of relational database normalization, which of the following statements is/are true?

Your answerSelect all correct options. You can choose more than one.

It is always possible to obtain a dependency-preserving 3NF decomposition of a relation

It is always possible to obtain a dependency-preserving 1NF decomposition of a relation

It is not always possible to obtain a dependency-preserving BCNF decomposition of a relation

It is not always possible to obtain a dependency-preserving 2NF decomposition of a relation

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In the context of schema normalization in relational DBMS, consider a set

of functional dependencies. The set of all functional dependencies implied by

is called the closure of

. To compute the closure of

, Armstrong’s axioms can be applied. Consider

, and

as sets of attributes over a relational schema. The three rules of Armstrong’s Axioms are described as follows.

Reflexivity: If

, then

Augmentation: If

, then

for any

Transitivity: If

and

, then

The additional rule of Union is defined as follows.

Union: If

and

, then

It can be proved that the additional rule of Union is also implied by the three rules of Armstrong’s Axioms. Listed below are four combinations of these three rules. Which one of these combinations is both necessary and sufficient for the proof?

Your answerChoose one option.

Reflexivity, Augmentation, and Transitivity

Reflexivity and Augmentation

Transitivity

Augmentation and Transitivity

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Consider a relational database schema with two relations

and

. Let

be a tuple relational calculus expression. Which one of the following relational algebraic expressions is equivalent to

Your answerChoose one option.

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An index in a DBMS is said to be dense if an index entry appears for every search-key value in the indexed file. Otherwise it is called a sparse index. Consider the following two statements.

S1: A hash index must be a dense index

S2: A

tree index can be a sparse index

Which one of the following options is correct?

Your answerChoose one option.

Both S1 and S2 are true

Both S1 and S2 are false

S1 is true and S2 is false

S1 is false and S2 is true

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Consider a relational database schema with a relation

. If

and

are the only two candidate keys of the relation

, then the number of superkeys of relation

is _____. (answer in integer)

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A schedule of three database transactions

, and

is shown.

and

denote read and write of data item

by transaction

. The transaction

aborts at the end. Which other transaction(s) will be required to be rolled back?

Your answerChoose one option.

Only

Both

and

Neither

nor

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Consider the following

tree with 5 nodes, in which a node can store at most 3 key values. The value 23 is now inserted in the

tree. Which of the following option(s) is/are CORRECT?

Tree diagram: root keys 6, 12, 19; four leaf nodes contain, respectively, 1, 4, 3; 7, 9, 10; 13, 15, 17; and 20, 21, 22.

Diagram for Computer Science and Information Technology question 21

Your answerSelect all correct options. You can choose more than one.

None of the nodes will split.

At least one node will split and redistribute.

The total number of nodes will remain same.

The height of the tree will increase.

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GATE CSE Databases PYQs

How to practice Databases

Question 15

Question 20

Question 30

Question 31

Question 42

Question 43

Question 46

Question 65

Question 15

Question 21