Oracle Bitmap Indexes and PostgreSQL Bitmap
Feature compatibility | AWS SCT / AWS DMS automation level | AWS SCT action code index | Key differences |
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PostgreSQL doesn’t support BITMAP index. You can use BRIN index in some cases. |
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.
Examples
Create an Oracle bitmap index.
CREATE BITMAP INDEX IDX_BITMAP_EMP_GEN ON EMPLOYEES(GENDER);
For more information, see CREATE INDEX
PostgreSQL Usage
Amazon Aurora PostgreSQL doesn’t currently provide a directly comparable alternative for Oracle bitmap indexes.