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Oracle® Database Reference
10g Release 1 (10.1)

Part Number B10755-01
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CREATE_BITMAP_AREA_SIZE

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 the CREATE_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