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Initialization Parameters
Oracle8i (and 9i with shared server)
- CREATE_BITMAP_AREA_SIZE
- BITMAP_MERGE_AREA_SIZE
- COMPATIBLE
Oracle9i with dedicated server
- WORKAREA_SIZE_POLICY = AUTO
- PGA_AGGREGATE_TARGET
Notes:
CREATE_BITMAP_AREA_SIZE – This parameter determines the amount of memory allocated for bitmap creation. The default value is 8 Mb. A larger value may lead to faster index creation. If cardinality is very low, you can set a small value for this parameter. For example, if cardinality is lower than 10 then the value can be on the order of kilobytes rather than megabytes. The higher the cardinality the higher the value you should set for CREATE_BITMAP_AREA_SIZE.
BITMAP_MERGE_AREA_SIZE – This parameter determines the amount of memory used to merge bitmaps retrieved from a range scan of the index. The default value is 1 Mb. Because a bitmap segment must be sorted before being merged into a single bitmap, a larger merge area should improve performance.
For Oracle9i databases running in dedicated mode, Oracle recommends using automatic PGA management. This is enabled with WORKAREA_SIZE_POLICY=AUTO and setting PGA_AGGREGATE_TARGET equal to the memory you want to dedicate for all sessions and processes connected to the instance.
Refer to the Oracle Database Reference for more information on these parameters.