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subbu_mareedu
Starting Member

11 Posts

Posted - 2014-04-16 : 14:21:17
Hai friends

Can u tell me about cover indexes?
When we are using this indexes & give the example?

Regards
Subbu

subbu

TG
Master Smack Fu Yak Hacker

6065 Posts

Posted - 2014-04-16 : 14:42:39
A more accurate term is "covered query". This means the index(es) include all columns referenced by the query. sql server then only needs to access the index and does not need to access the table when executing the query.

For more details and examples have a look at Creating Indexes with Included Columns

EDIT:
The reason I don't like the term "covered index" is because an index on its own cannot be covered. It can only be considered covering a specific query. Once you change your query to reference more columns, columns which are not covered by this index, then the same index is no longer "covering".

Be One with the Optimizer
TG
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subbu_mareedu
Starting Member

11 Posts

Posted - 2014-04-17 : 13:08:24
Thanks TG


subbu
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