Why non-clustered index is needed ?

Posted by Akiii under Sql Server on 4/6/2011 | Points: 10 | Views : 3371 | Status : [Member] | Replies : 3
I have read the article posted in dotnetfunda section. Below is the link..

http://www.dotnetfunda.com/interview/exclusive/x4248-net-and-sql-server-interview-question-what-are-difference-between-cluste-.aspx

But why do we need to have a non-clustered index if it is eventually pointing the clustered index ??
Can anyone clarify this with an example ??

Thanks and Regards
Akiii




Responses

Posted by: Raja on: 4/6/2011 [Member] Starter | Points: 25

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Very good question Akii,

Here is some good stuffs, I have not gone through them but I have researched and found that these post will be useful to you to understand why Non-Clustered index is required. Once you know kindly update this thread with the answer

http://social.msdn.microsoft.com/Forums/en-US/sqldatabaseengine/thread/b92148ea-aa90-4854-a95d-2a2a19df59f4
http://msdn.microsoft.com/en-us/library/ms177484.aspx
http://msdn.microsoft.com/en-us/library/aa933130(v=sql.80).aspx

Hope this will help and let us know the summary of going through above articles.

Thanks

Regards,
Raja, USA

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Posted by: Karthikanbarasan on: 4/6/2011 [Member] [Moderator] [Microsoft_MVP] [MVP] Silver | Points: 25

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Nice links Raja!!!

Thanks
Karthik
www.f5Debug.net

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Posted by: Akiii on: 4/6/2011 [Member] Bronze | Points: 25

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@Raja....thanks for the links......i have made a small extract:-

For a clustered index, the database will sort the table's records according to the column specified by the index. A clustered index contains all of the data for a table in the index, sorted by the index key, just like a phone book is sorted by name and contains all of the information for the person inline. The non-clustered indexes contain only the index key and a reference to find the data, which is more like a book index. A book index stores words in order with a reference to the page numbers where the word is located. You can only create one clustered index on each table.

I hope the above information is correct.....

Can u tell me when can we use non-clustered index in real life projects ??

Thanks and Regards
Akiii

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