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bala012
Starting Member
4 Posts |
 Posted - 2014-05-05 : 12:14:14
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| Hi,I have a question regarding indexes.If i have cluster and NC index on same column,does it degrade performance on DML statements ? any advantage on select statements.Is it good to have both indexes on same column ? |
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Lamprey
Master Smack Fu Yak Hacker
4614 Posts |
Posted - 2014-05-05 : 12:38:33
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| Indexes have overhead. So, yes there is some performance hit for everything that changes the data. If the indexes are exactly the same, then remove the non-clustered one. If it is different somehow, then it might make sense to keep it. But, in general it is not a good idea to have a clustered and an non clustered index on the same column. |
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Ifor
Aged Yak Warrior
700 Posts |
Posted - 2014-05-07 : 05:38:30
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| Be aware that removing the NC index can cause blocking if foreign keys are used.Placing a clustered and non-clustered index on a column is the only way to stop foreign key lookups and insert/update/delete blocking each other in a high transaction environment. |
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CI and NC index on same column