Database Questions & Answers – Bitmap Indices

This set of Database Multiple Choice Questions & Answers (MCQs) focuses on “Bitmap Indices”.

1. Bitmap indices are a specialized type of index designed for easy querying on ___________
a) Bit values
b) Binary digits
c) Multiple keys
d) Single keys
View Answer

Answer: a
Explanation: Bitmap indices are a type of index that is optimized for efficient querying on columns containing boolean or bit values. Each value in the column has a corresponding bitmap, with each bit representing a row. This enables fast querying and filtering of large datasets.

2. A _______ on the attribute A of relation r consists of one bitmap for each value that A can take.
a) Bitmap index
b) Bitmap
c) Index
d) Array
View Answer

Answer: a
Explanation: A bitmap is simply an array of bits.


WHERE gender = ’f’ AND income level = ’L2’;

In this selection, we fetch the bitmaps for gender value f and the bitmap for income level value L2, and perform an ________ of the two bitmaps.
a) Union
b) Addition
c) Combination
d) Intersection
View Answer

Answer: d
Explanation: We compute a new bitmap where bit i has value 1 if the ith bit of the two bitmaps are both 1, and has a value 0 otherwise.

4. To identify the deleted records we use the ______________
a) Existence bitmap
b) Current bitmap
c) Final bitmap
d) Deleted bitmap
View Answer

Answer: a
Explanation: The bitmaps which are deleted are denoted by 0.

5. Bitmaps can be used as a compressed storage mechanism at the leaf nodes of ________ for those values that occur very frequently.
a) B-trees
b) B+-trees
c) Bit trees
d) Both B-trees and B+-trees
View Answer

Answer: b
Explanation: Bitmaps are combined and stored in a B+ tree.

6. Bitmaps can be combined with regular B+-tree indices for relations where a few attribute values are extremely common, and other values also occur, but much less frequently.
a) Bitmap, B-tree
b) Bitmap, B+tree
c) B-tree, Bitmap
d) B+tree, Bitmap
View Answer

Answer: b
Explanation: Bitmaps are combined and stored in a B+ tree.

7. In a B+-tree index ______ for each value, we would normally maintain a list of all records with that value for the indexed attribute.
a) Leaf
b) Node
c) Root
d) Link
View Answer

Answer: a
Explanation: Bitmaps are combined and stored in a B+ tree.

8. A tablespace is further broken down into ________
a) Tablespace
b) Segments
c) Extents
d) Blocks
View Answer

Answer: b
Explanation: Segment names are used in create table and create index commands to place tables or indexes on specific database devices.

9. In ordered indices the file containing the records is sequentially ordered, a ___________ is an index whose search key also defines the sequential order of the file.
a) Clustered index
b) Structured index
c) Unstructured index
d) Nonclustered index
View Answer

Answer: a
Explanation: Clustering index are also called primary indices; the term primary index may appear to denote an index on a primary key, but such indices can in fact be built on any search key.

10. Indices whose search key specifies an order different from the sequential order of the file are called ___________ indices.
a) Nonclustered
b) Secondary
c) All of the mentioned
d) None of the mentioned
View Answer

Answer: c
Explanation: Nonclustering index are also called secondary indices.

Sanfoundry Global Education & Learning Series – Database Management System.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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