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Dual Bitmap Index: Space-Time Efficient Bitmap Index for Equality and Membership Queries

Indexing techniques based on bitmap representations are known to improve query response time in a data warehouse environment. Specifically, bitmap indexing is a good method for improving complex and ad hoc queries without adding additional hardware. This method improves query processing using large numbers of fast Boolean operations and multiple index scans. By performing simple predicate conditions on the index level before going to the primary data source, the average query response time is improved. In this paper, we introduce dual bitmap index that uses less space than existing bitmap indices while maintaining the same improvements in query processing speed. The dual bitmap index represents each attribute value using only two bitmap vectors, with each bitmap vector representing many attribute values. This paper shows a comparative study of five bitmap indexing techniques, and shows that the dual bitmap index is more efficient than the existing techniques for equality and membership queries from a space-time trade-off perspective