Integer 

Static 

8388608 (8 MB) 

Operating system dependent 

CREATE_BITMAP_AREA_SIZE is relevant only for systems containing bitmap indexes. It specifies the amount of memory allocated for bitmap creation. The default value is 8 MB. A larger value may speed up index creation.

Cardinality is the number of unique values in a column in relation to the number of rows in the table. If cardinality is very small, you can set a small value for this parameter. For example, if cardinality is only 2, then the value can be on the order of kilobytes rather than megabytes. As a general rule, the higher the cardinality, the more memory is needed for optimal performance.

See Also: Oracle8i Designing and Tuning for Performance for more information on using bitmap indexes.