| Property | Description |
|---|---|
| Parameter type | Integer |
| Default value | 8388608 (8 MB) |
| Modifiable | No |
| Range of values | Operating system-dependent |
| Basic | No |
Note:
Oracle does not recommend using theCREATE_BITMAP_AREA_SIZE parameter unless the instance is configured with the shared server option. Oracle recommends that you enable automatic sizing of SQL working areas by setting PGA_AGGREGATE_TARGET instead. CREATE_BITMAP_AREA_SIZE is 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