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46 votes
46 votes

An index is clustered, if

  1. it is on a set of fields that form a candidate key
  2. it is on a set of fields that include the primary key
  3. the data records of the file are organized in the same order as the data entries of the index
  4. the data records of the file are organized not in the same order as the data entries of the index

3 Answers

Best answer
35 votes
35 votes

Answer is C).

Index can be created using any column or combination of column which need not be unique. So, A, B are not the answers.

Indexed column is used to sort rows of table.Whole data record of file is sorted using index so, C is correct option. (Simple video explains this).

edited by
26 votes
26 votes

Clustered Index is created on data file whose file recordrds are physically ordered on a non key field which does not have distinct value for each record .

Option A ) Candidate Key

Option B) Primary Key

Option D ) File NOT ordered

Best choice  is Option C

Option C ) Data records are ordered

edited by
0 votes
0 votes

Just adding up more points:

Option A): Indexing based on Candidate keys can be done using Primary index or Secondary Index given ordered/unordered data records

Option B): Indexing based on primary key also a candidate key so the same logic applies as option A

Option C): Indexing on ordered/organized data records over non key value attribute is mandatory for clustering index

Option D) Indexing on Unordered data records over key/non key attribute is for secondary indexing 

Answer C.

For more on Cluster indexing: https://stackoverflow.com/questions/1251636/what-do-clustered-and-non-clustered-index-actually-mean

 

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