HOLAP (Hybrid Online Analytical Processing) is a combination of ROLAP (Relational OLAP) and MOLAP (Multidimensional OLAP). HOLAP allows storing part of the data in a MOLAP store and another part of the data in a ROLAP store.
HOLAP can use varying combinations of ROLAP and OLAP technology. It typically stores data in both a relational database and a multidimensional database, depending on the preferred type of processing. The databases are used to store data in the most functional way possible. For heavy data processing, the data is more efficiently stored in a relational database, whereas multidimensional bases are used for speculative processing.