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What is a Clustered Index

 
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MikePradeep

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Joined: 05 Jan 2007
Posts: 5
Location: Bangalore

PostPosted: Fri Jan 12, 2007 9:22 am    Post subject: What is a Clustered Index
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Hi,

I want to know the difference between a clustered Index and a non-clustered index. And also why we need a clustered Index.
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priyesh.agrawal

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Joined: 28 Mar 2005
Posts: 1452
Location: Chicago, IL

PostPosted: Fri Jan 12, 2007 10:30 am    Post subject: Re: What is a Clustered Index
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I want to know the difference between a clustered Index and a non-clustered index

Let's make it little simpler, Clustered Index is Primary Index and Non-clustered Index is Secondary Index.

Now suppose an index "EMP_IDX" has been defined on a column say "DEPT" on a TABLE "EMP_TBL", so in case of a clustered index all the values for the same "DEPT" would be stored in the same block/area of database memory else its a Non-clustered index.

Quote:
And also why we need a clustered Index.

Now how do you expect for a Select query to behave where you want to have all EMP_NAME for any specific "DEPT".
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