GATE | GATE CS 2008 | Question 15

A clustering index is defined on the fields which are of type
(A) non-key and ordering
(B) non-key and non-ordering
(C) key and ordering
(D) key and non-ordering


Answer: (A)

Explanation: A clustering index as the name suggests is created when the data can be grouped in the form of clusters.

yashika

For example: A small database file storing roll no and subjects enrolled for a particular student. Here data can be grouped on the basis of Roll No.s.



Hence to create such kind of index files, fields could be non-key attributes and which are in ordered form so as to form clusters easily.
Hence option (A) – non key and ordering.
Additional points for Clustered Indexing:
1. The number of entries in the index file
are the unique values of the attribute on which indexing is done.
2. The pointer in the index file will give the base address of the block in which the value appear for the first time.

http://quiz.geeksforgeeks.org/indexing-in-databases-set-1/

This solution is contributed by Yashika Arora.

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