New Features for Administrators - Question 086

A bitmap join index is defined as __________.

A. An index used to join two bitmap indexes on a table

B. A bitmap index created for the join of two or more tables

C. A bitmap index created on the join of two or more indexes

D. A bitmap index created on the join of two or more indexed-organized tables

Answer: B

Explanation:

Prior to Oracle9i, you could create bitmap indexes on a single table. Bitmap indexes are very useful in data warehousing environment for low-cardinality columns. Oracle9i extents this concept to a bitmap join index that optimizes the joining of two or more tables. A bitmap join index is a space- and performance-efficient technique. By predetermining associations, bitmap join indexes eliminate the large volumes of data generated with Cartesian products performed in a join operation.

Incorrect Answers

A: A bitmap join index is not a join of two bitmap indexes on a table.

C: A bitmap index created on the join of two or more tables, not indexes.

D: You cannot reference an IOT or a temporary table.

OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 142-143 Chapter 3: Manageability Enhancements

Oracle 9i New Features, Robert Freeman, p. 54-56 Chapter 2: Oracle9i Architecture Changes