250+ TOP MCQs on Bitmap Indices and Answers

RDBMS Multiple Choice Questions on “Bitmap Indices”.

1. A bitmap is _______
a) An array of bits
b) An index of bits
c) A function mapping all the bits of data
d) None of the mentioned

Answer: a
Clarification: A bitmap is simply an array of bits. A bitmap can be used for various purposes such as bitmap indexing.

2. A _________ on the attribute A of relation r consists of one bitmap for each value that A can take
a) Bitmap array
b) Bitmap index
c) Bitmap excess
d) Bitmap

Answer: b
Clarification: A bitmap index on the attribute A of relation r consists of one bitmap for each value that A can take. Each bitmap contains as many bits as the number of records in the relation.

3. Intersection of the bitmaps is done by
a) Logical AND
b) Logical OR
c) Logical NOT
d) Logical NOR

Answer: a
Clarification: The intersection of the bitmaps is done by the logical AND operation. This is similar to the binary set intersection operation which is done by the logical AND operation.

4. What does an existence bitmap do?
a) It recognizes deleted records
b) It inserts values into empty bitmaps
c) It makes sure that no records are deleted
d) None of the mentioned

Answer: a
Clarification: An existence bitmap is used to recognize deleted records and not to prevent deletion of records. It also does not insert any records into empty bitmaps.

5. The complement operation in bitmaps is done by using
a) Logical AND
b) Logical OR
c) Logical NOT
d) Logical NOR

Answer: c
Clarification: The complement operation in bitmaps is done by using the logical not operator. This is similar to the binary complement operation.

6. State true or false: Bitmaps can be combined with B+ trees
a) True
b) False

Answer: a
Clarification: Bitmaps can be combined with B+ trees for relations where a few attribute values are extremely common.

7. We create an index in SQL using _______ command
a) Create index
b) New index
c) Create new index
d) Develop index

Answer: a
Clarification: We create an index in SQL using the create index command. Eg: create index dept_index on instructor(dept_name).

8. We delete and index in SQL using the ________ command
a) Remove index
b) Delete index
c) Drop index
d) None of the mentioned

Answer: c
Clarification: We delete and index in SQL using the drop index command. Syntax: drop index ;

9. State true or false: Intersection operations are extremely slow on bitmaps
a) True
b) False

Answer: b
Clarification: Intersection operations are extremely fast on bitmaps making them ideal for supporting queries on multiple attributes.

10. Which of the following operations is used for the union of bitmaps?
a) Logical AND
b) Logical OR
c) Logical NOT
d) Logical NOR

Answer: b
Clarification: The logical OR operation is used for the computation of the union of bitmaps. This is similar to the binary set union operation.