Physical Database Design

4.2 Indexing Rules of Thumb 55

7. Dense versus sparse index: A dense index has a pointer to each row in the table;

a sparse index has at most one pointer to each block or page in the table.

This list contains different types of index structures: B+tree, hash index, bitmap,

and sparse/dense. It also contains different of ways of using these index structures: com-

posite index, clustered index, covering index. These can be combined in certain ways.

For in-stance, a user can create a composite index for a B+tree index. Similarly, a user

can create a unique index using a B+tree or hash index structure.

Indexes for join operations are the same types as those used for single table

indexes—they are simply applied in turn for each table involved in a join. ...