Expert Indexing in Oracle Database 11g: Maximum Performance for Your Database

Performance Implications Querying with Bitmap Indexes

Bitmap indexes are primarily built to aid in performance, especially in the data warehouse environment. The key performance benefits of using bitmap indexes include the following:

• Query speed improves with the use of a bitmap index over the traditional B-tree index.
• Creation speed of a bitmap index is far faster than that of a comparable B-tree index.
• Maintenance operations such as rebuilding indexes are much faster with a bitmap index.

One of the key reasons for some of these benefits is simply because the bitmap index is so much smaller than its B-tree equivalent. Of course this assumes you have created the bitmap index on lower cardinality columns. All these benefits being said, the primary ...