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ROLAP vs. MOLAP[edit]

ROLAP vs. MOLAP is a complicated discussion. Please do not add opinions to this article -- please respect the Neutral Point of View.

This discussion is even more complicated by the fact that there are many ROLAP and MOLAP products, and they are all different. Therefore limitations of some particular ROLAP or MOLAP tool should not be generalized to the whole subject area. Please only state the facts and omit speculations and opinions.

I'll add this remark: this statement "MOLAP differs significantly in that (in some software) it requires the pre-computation and storage of information in the cube — the operation known as processing." is not useful as a definition since (by its own admission) it doesn't cover all MOLAP tools.

The real difference between MOLAP and ROLAP is that ROLAP doesn't store its own data. ROLAP systems define a model and pull the data from a relational source on the fly. MOLAP stores base data. SOME MOLAP systems also precalculate some aggregate data, but some (most of the ones listed in the article in fact) do not.

As a reference, see the Wikipedia article on MSTR -- ROLAP is a "relational database access system using semantically dynamic objects" according to a lawsuit between BOBJ and MSTR.

Of course the boundaries are fading, especially if ROLAP systems like MicroStrategy are marketing their caches as MOLAP cubes. It's not an unreasonable claim by MSTR, but it makes defining things a lot harder ;-) — Preceding unsigned comment added by (talk) 13:05, 11 April 2013 (UTC)

To: Thank you for ammending my point instead of deleting it. I think it's good to leave the explanation that some MOLAP tools (Essbase) have the practical 10 dimension limit while others (MS AS) do not. Arcann 04:30, 2 January 2006 (UTC)


This article could have more information about what a multi-dimensional database and cubes are. There is some very simple, well explained, content in the Oracle RPAS user guide[1]. It would be nice to include some of this type of information here for non-technical people to understand. MaryEFreeman (talk) 13:45, 17 January 2013 (UTC)

  1. ^ "Retail Predictive Analysis Server User Guide", December 2012, Oracle© Corporation.

Merge discussion[edit]