Database Reference
In-Depth Information
Figure 21.2
A BTree Index on
Numbers 1 to 100.
more tables. Clusters can be ordered using binary tree structures or
hashing algorithms. A cluster is perhaps conceptually both a table
and an index because clustering partially merges index and data
spaces into single physical chunks (clusters).
Bitmap Join Index
. Creates a single bitmap used for one of the
tables in a join.
Domain Index
. Specific to certain application types using contextual
or spatial data, among other variations.
Note:
It usually is best, especially for OLTP systems, to use only BTree and
function-based index types. Other index types are more appropriate to data
warehouse systems that have primarily static, read-only tables.
21.1.2.1
Index Attributes
In addition to the type of index, Oracle Database 10
supports what I like
to call index attributes. Most types of indexes can use these attributes. You
will practice using some of these attributes as you work through this chapter
creating and modifying indexes.
g
Ascending or Descending
. Indexes can be ordered in either direction.
