Which statement is not correct?

a. Multidimensional OLAP (MOLAP) stores the multidimensional data using a multidimensional DBMS (MDBMS) whereby the data are stored in a multidimensional array-based data structure optimized for efficient storage and quick access.

b. Relational OLAP (ROLAP) stores the data in a relational data warehouse, which can be implemented using a star, snowflake, or fact constellation schema. c. Hybrid OLAP (HOLAP) tries to combine the best of both MOLAP and ROLAP. An RDBMS can then be used to store the detailed data in a relational data warehouse, whereas the pre-computed aggregated data can be kept as a multidimensional array managed by an MDBMS.

d. MOLAP scales better to more dimensions than ROLAP. The query performance may, however, be inferior to ROLAP unless some of the queries are materialized or high-performance indexes are defined.