BITMAP_MERGE_AREA_SIZE

Parameter type	Integer
Default value	1048576 (1 MB)
Parameter class	Static
Range of values	Operating system-dependent

Note: Oracle does not recommend using the BITMAP_MERGE_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. BITMAP_MERGE_AREA_SIZE is retained for backward compatibility.

BITMAP_MERGE_AREA_SIZE is relevant only for systems containing bitmap indexes. It specifies the amount of memory Oracle uses to merge bitmaps retrieved from a range scan of the index. The default value is 1 MB. A larger value usually improves performance, because the bitmap segments must be sorted before being merged into a single bitmap.

See Also: Oracle9i Database Performance Tuning Guide and Reference for more information on setting this parameter