OLAP Variants: Molap, Rolap, & Holap

Source: Greiner, L. (2010). Data analysis and data mining. Faulkner Information Services.


**OLAP Variants: MOLAP, ROLAP, and HOLAP. **

OLAP is divided into multidimensional OLAP (MOLAP),
relational OLAP (ROLAP), and hybrid OLAP (HOLAP).
ROLAP can be applied both as a powerful DSS product, as well as to aggregate and pre-stage multidimensional
data for MOLAP environments. ROLAP products optimize data for multi-dimensional analysis
using standard relational structures. The advantage of the MOLAP paradigm is that it can natively
incorporate algebraic expressions to handle complex, matrix-based analysis. ROLAP, on the other hand,
excels at manipulating large data sets and data acquisition, but is limited to SQL-based functions. Since
all organizations will require both complex analysis and analysis of large data sets, it could be necessary
to develop an architecture and set of user guidelines that will enable implementation of both ROLAP and
MOLAP where each is appropriate.
HOLAP is the newest step in the ongoing evolution of OLAP. HOLAP combines the benefits of both
ROLAP and MOLAP by storing only the most often used data in multidimensional cube format and
processing the rest of the relational data in the standard on-the-fly method. This provides good
performance in browsing aggregate data, but slower performance in "drilling down" to further detail.

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