|Range of values||Operating system-dependent|
Note:Oracle does not recommend using the
CREATE_BITMAP_AREA_SIZEparameter unless the instance is configured with the shared server option. Oracle recommends that you enable automatic sizing of SQL working areas by setting
CREATE_BITMAP_AREA_SIZEis retained for backward compatibility.
CREATE_BITMAP_AREA_SIZE is relevant only for systems containing bitmap indexes. It specifies the amount of memory (in bytes) 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:Oracle Database Performance Tuning Guide for more information on using bitmap indexes