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Are indexes nesessary to perform data retrieval

 
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ratheesh_1983

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Joined: 11 Apr 2007
Posts: 19
Location: hyderabad

PostPosted: Thu Jul 12, 2007 2:33 pm    Post subject: Are indexes nesessary to perform data retrieval
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hi all,

Are indexes nesessary to perform data retrieval operations on a table? I have heard that db2 "need not" use the index while doing table operation icon_exclaim.gif .
then , supposing that performance is not an issue , can we use tables without indices??

thanks in advance,
Ratheesh.
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muthuvel

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Joined: 29 Nov 2005
Posts: 217
Location: Chennai

PostPosted: Thu Jul 12, 2007 3:21 pm    Post subject: Re: Are indexes nesessary to perform data retrieval
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It is not a must that each and every table should have an index.
As you have said,index is to improve the perfromance and provide faster access to data.
Each index is based on the values of data in one or more columns of a table.Improve performance and Ensure uniqueness are the key factors of indexing.
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dick scherrer

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Joined: 23 Nov 2006
Posts: 19270
Location: Inside the Matrix

PostPosted: Thu Jul 12, 2007 10:04 pm    Post subject:
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Hello,

Hopefully, it is realized that if there are no key definition(s) every time the table is read every row in the table will be read - the code may choose to skip unwanted rows, but every one must be read.
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