UGC NET CSE | June 2014 | Part 2 | Question: 48

Question

A clustering index is created when _______. 

• A. Primary key is declared and ordered 
• B. No key ordered
• C. Foreign key ordered
• D. There is no key and no order 

Answer 1

A clustering index  = ( non key attribute + ordered )

so C is the answer

Comments

we have to see which FK is sorted  .

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We are going away from the question. By default a clustering index is created on primary key unless we explicitly say "NONCLUSTERED" or declare another clustered index. 

Ref: http://blogs.msdn.com/b/sqlgardner/archive/2013/03/28/primary-keys-and-the-default-clustered-index.aspx

Ref: http://dba.stackexchange.com/questions/7741/when-should-a-primary-key-be-declared-non-clustered

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I`m totally agree with you . My point is if any key that is sorted can form clustered index . In case of  of primary key the size of clustered index will be more than a non key attribute ( because data can be repeated in case of non key attribute) . and we have opportunity  to create primary index which is more efficient  in case of primary key .

REF : https://technet.microsoft.com/en-us/library/ms190639(v=sql.105).aspx

 so , ans will be A and C  ? 

Answer 2

ans=>B

no key required and it is ordered

http://stackoverflow.com/questions/5070529/difference-between-clustered-and-nonclustered-index?lq=1

Comments

http://www.brightways.org/ugc-net-computer-science-june-2014-answer-key-paper2.php?page=5#!

Answer 3

Ans- A clustering index is created when primary key is declared and ordered.

Comments

if there is no primary key then CI automatically assumes a 4 bit identifier..which means no need of primary key