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Clustered vs. Nonclustered Expand / Collapse
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Posted Friday, April 19, 2013 4:46 PM
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I just finished learning about clustered and nonclustered indexes and I was wondering a few things since I doubt I fully grasp these concepts yet. With nonclustered indexes, you can make them convering indexes by adding filters and INCLUDE column to make them as efficient as clustered indexes, so why use clustered indexes? Or is it because you can only use one clustered index per table, that you need to use nonclustered indexes? Again, I just finished learning these concepts the past few days so I'm trying to fully understand them.
Post #1444640
Posted Friday, April 19, 2013 4:49 PM


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Here are a few resources that would be of benefit to you in trying to learn about indexes

http://www.sqlservercentral.com/stairway/72399/

And
http://www.sqlservercentral.com/articles/Indexing/68439/




Jason AKA CirqueDeSQLeil
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Post #1444643
Posted Friday, April 19, 2013 4:51 PM
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Oh wow thanks for those links.
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Posted Friday, April 19, 2013 4:52 PM


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You're welcome.



Jason AKA CirqueDeSQLeil
I have given a name to my pain...
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Hidden RBAR - Jeff Moden
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Post #1444645
Posted Friday, April 19, 2013 5:12 PM
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While we are on the topic, "seek" and "lookup" seem like the same thing, at least in terms of their syntax and what they're trying to accomplish. I'm assuming with a seek, you can do multiple rows where with a lookup you can only do one row/column.
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Posted Saturday, April 20, 2013 5:00 AM


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http://www.sqlservercentral.com/articles/Indexing/68439/
http://www.sqlservercentral.com/articles/Indexing/68563/
http://www.sqlservercentral.com/articles/Indexing/68636/
http://sqlinthewild.co.za/index.php/category/sql-server/indexes/


Seek - navigation down the b-tree of an index to locate a row or the start or end of a range of rows.
Lookup - single-row seek on the clustered index to fetch the rest of the columns necessary for the query.



Gail Shaw
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