Comments on: Back To Basics: What are indexes and what are they used for? http://itknowledgeexchange.techtarget.com/sql-server/back-to-basics-what-are-indexes-and-what-are-they-used-for/ Tue, 07 May 2013 13:39:52 +0000 hourly 1 By: mrdenny http://itknowledgeexchange.techtarget.com/sql-server/back-to-basics-what-are-indexes-and-what-are-they-used-for/#comment-176 mrdenny Wed, 28 Jan 2009 00:29:25 +0000 http://itknowledgeexchange.techtarget.com/sql-server/back-to-basics-what-are-indexes-and-what-are-they-used-for/#comment-176 Acapsis,
The clustered index must be on the same file group as the table.

The nonclustered index can be placed on the same file group, on in a different file group.

By default the primary key will be the clustered index unless you tell it otherwise. Depending on how you are querying the table you may need to have more than one index on this linking table. I have several linking tables which I need to be able to query from both sides (mine are only two columns wide) and I have two indexes on each. The clustered index with the first column as the first column in the index, and the second index with the second column as the indexed column, and the first column as an included column.

]]> By: Acapsis http://itknowledgeexchange.techtarget.com/sql-server/back-to-basics-what-are-indexes-and-what-are-they-used-for/#comment-174 Acapsis Mon, 26 Jan 2009 22:28:28 +0000 http://itknowledgeexchange.techtarget.com/sql-server/back-to-basics-what-are-indexes-and-what-are-they-used-for/#comment-174 I have inheirited three tables with many to many relationships,
and another so called link table containing three foreign keys in each
record. Is the correct index for the link table – a single clustered index
using all three columns? Should clustered indexes be on the primary
file group and non clustered go else where? where exactly?

Many thanks…

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