Understanding Index Structures
As we discussed earlier in this chapter, index structures are divided into two basic components of the index: the leaf level and the non-leaf level(s). The details in this section help you to better understand what’s specifically stored within these portions of your indexes and how they differ based on index type.
The Dependency on the Clustering Key
The leaf level of a clustered index contains the data, not just the index keys. So the answer to the question “What else is in the leaf level of a clustered index besides the key value?” is “Everything else”—that is, all the columns of every row in the table are in the leaf level of a clustered index. Another way to say this is that when a clustered index is created, the ...
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