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Bitmap Indexes

Oracle Usage

Bitmap indexes are task-specific indexes best suited for providing fast data retrieval for OLAP workloads and are generally very fast for read-mostly scenarios. However, bitmap indexes don’t perform well in heavy DML or OLTP workloads.

Unlike B-tree indexes where an index entry points to a specific table row, a bitmap index stores a bitmap for each index key.

Bitmap indexes are ideal for low-cardinality data filtering where the number of distinct values in a column is relatively small.

Example

Create an Oracle bitmap index.

CREATE BITMAP INDEX IDX_BITMAP_EMP_GEN ON EMPLOYEES(GENDER);

For more information, see CREATE INDEX in the Oracle documentation.

MySQL Usage

Currently, Amazon Aurora MySQL doesn’t provide a comparable alternative for bitmap indexes.