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sportsguy
Starting Member
39 Posts |
 Posted - 2013-12-01 : 15:54:39
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| I have created a SS warehouse, so perfect normalization is not a requirement. I have created non unique indexes of 5-7 columnsMy question is:for these 5-7 fields, should I create one index of 5-7 fields,or 5-7 individual indexes?thanks in advance. . .sportsguyMS Access 20 years, SQL hack |
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visakh16
Very Important crosS Applying yaK Herder
52326 Posts |
Posted - 2013-12-02 : 04:35:26
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| depends on how you use these columns in the queries. whats the frequency of using them together for filtering.selecting against using them separately?------------------------------------------------------------------------------------------------------SQL Server MVPhttp://visakhm.blogspot.com/https://www.facebook.com/VmBlogs |
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TG
Master Smack Fu Yak Hacker
6065 Posts |
Posted - 2013-12-02 : 16:21:58
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| The thing to know for deciding on indexes is when the index will not be used. For instance:index1234 (col1, col2, col3, col4)this index will be used when filter and/or joining is done with:- all four columns- only these 3: col1, col2, col3- only these 2: col1, col2- only this: col1this index will not be for any other combination of columns. In other words look at the index columns from left to right. To use an index for a query that only filters on col3 then you need an index that either is only on col3 or starts with col3Be One with the OptimizerTG |
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SQL table indexing