OLAP technology can be further defined by the methods for storing and accessing data dn by the performance of queries against that data. SAS OLAP supports three different variations of OLAP technology:

(1)    MOLAP (multidimensional OLAP) is a type of OLAP that stores summaries of detail data (aggregates) in multidimensional database structures. MOLAP cubes are most suited for slicing and dicing of data and are used when performance and query speed is critical. For further information on MOLAP, see the topic MOLAP Aggregation Storage.

(2)    ROLAP (relational OLAP) is a type of OLAP in which multidimensional data is stored in a relational database such as a SAS table or an ORACLE table. ROLAP is more scalable than other OLAP types and handles extensive amounts of data well. Although performance can be somewhat slow, ROLAP is limited only by the size of the relational database it is identified with. For father information on ROLAP, see the topic ROLAP Aggregation Storage.

(3)    HOLAP (hybrid OLAP)  is a type of OLAP in which relational OLAP (ROLAP) and multidimensional OLAP (MOLAP) are combined. In HOLAP, the source data is usually stored using a ROLAP strategy, and aggregations are stored using a MOLAP strategy. It combines the best features of both ROLP and MOLAP. This combination usually results in the smallest amount of storage space. In HOLAP, aggregates can be pre calculated and can be linked into a hybrid storage model.

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