ISRO2018-51

Question

Which of the following is dense index?

• A. Primary index
• B. Clustered index
• C. Secondary index
• D. Secondary non-key index

Comments

Secondary index is dense index, option C is correct. Whereas, secondary non key index may or may not be dense index.

Answer 1

A. Primary index is maintain for the anchor value of block i,e one key value per block maintained in Index file.

B. Clustering index is basically mixed sort of Indexing i,e Dense as it is maintained for  unique value (key)  and Sparse as it is not maintained for every value.

C. Index is maintained for every key value so dense index.

ans. C

Comments

why not option d????

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Non-key means :- There will be repetition of values, so we will maintain index only for one of the repeated values. Since we left some of the values, hence not dense

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both c d are correct source navathe

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Sonam mam can we challenge isro key??I selected d

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yes

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But mam here it is written dense  or  nondense

So will take isro take it for Grant?

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Yes, Sankha.

Because there might be situation when it is sparse. for example:-

Empid       -Dependent id

1                    A

1                    B

2                    c

3                     D

Now secondary index when made on Empid, then we will not maintain two entry for 1. There will be only one entry. Since we left some repeated values hence sparse

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Index entry will be created for every search key value

Your example is clustered index

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One more in support of options D

http://www.cs.montana.edu/~halla/csci440/n18/n18.html

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So is this wrong:

http://www.eazynotes.com/pages/database-management-system/indexing.html

Answer 2

Ref: Navathe