By the same token, there is a type of duplicate index that can provide huge performance increases. They usually (but not always) are considered to be
"Covering Indexes". You can have the "perfect" Clustered Index for your query but, unless you're using a huge number of columns from a very wide table in your query, a much narrower Non-Clustered Index with the exact same key as the Clustered Index and the correct INCLUDES (think of it as being very similar to a much smaller Clustered Index) can make the queries that use the Non-Clustered Index absolutely fly compared to when the query uses the Clustered Index simply because of the greatly reduced page count thanks to more rows per page in the Non_Clustered Index.
is pronounced ree-bar and is a Modenism for R
First step towards the paradigm shift of writing Set Based code: Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.
If you think its expensive to hire a professional to do the job, wait until you hire an amateur. -- Red Adair
When you put the right degree of spin on it, the number 318
is also a glyph that describes the nature of a DBAs job. Helpful Links:
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