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Aged Yak Warrior

570 Posts

Posted - 06/27/2009 :  16:00:33  Show Profile  Reply with Quote
Hi all,
I have a question.

When we have clustured index on a table, then entire row is stored at the leaf level, then

Wht is the significance of creating normal index on other column of the same table which has clustured index.


Flowing Fount of Yak Knowledge

8781 Posts

Posted - 06/27/2009 :  17:33:50  Show Profile  Visit webfred's Homepage  Reply with Quote
If you want to search often for that other column this "normal" index is speeding this.
The clustered index cannot be sorted to satisfy all searches...
In case of having a clustered index the "normal" index for the other column holds the information/search item for searching then in clustered index.

No, you're never too old to Yak'n'Roll if you're too young to die.
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Constraint Violating Yak Guru

332 Posts

Posted - 06/28/2009 :  03:32:41  Show Profile  Reply with Quote
Clustered index-->Reorders the way records in the table are physically stored. Therefore table can have only one clustered index.
The leafnodes of clustered index contain the data pages.
Table and index are same
Non- clustered index-->In which the logical order of the index does not match the physical stored order of the rows on disk
The leafnode of non clustered index does not consist of the data pages. Instead , the leaf nodes contain index rows.
Table and index are different from each other

Go through below link...hope it will help
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Aged Yak Warrior

595 Posts

Posted - 06/29/2009 :  10:16:28  Show Profile  Send rajdaksha a Yahoo! Message  Reply with Quote
A clustered index determines the physical order of data in a table. A clustered index is analogous to a telephone directory, which arranges data by last name. Because the clustered index dictates the physical storage order of the data in the table, a table can contain only one clustered index. However, the index can comprise multiple columns (a composite index), like the way a telephone directory is organized by last name and first name.

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Aged Yak Warrior

570 Posts

Posted - 07/09/2009 :  02:52:16  Show Profile  Reply with Quote
Thanks you for the reply, I got it... correct me If I am worng. there are only 3 types of allocation unit
1. In_row_data
2. Lob_data
3. Row_overflow_data

Any datatype (data rows) should fit into one of these there type of allocation unit.

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