What is Molap and Rolap? What is Diff between Them?

Answer Posted / marcelo malheiros

Hello Pratap,

Sorry but you are missing the some steps re retrieving
information from a cube...

As you may know, a cube can have its data stored in a RDBMS
(in tables).

In order to retrieve the data from the RDBMS, when the
frontend sends a MDX instruction to the cube, the cube has
to translate the MDX instruction into SQL and send the SQL
to the RDBMS. The RDBMS returns a table as result set from
the SQL statement. The cube reads that table (result set)
and converts it to a hierarchical result set. The
hierarchical result set is then sent to the front-end that
formats the information and displays it to the end-user...

So, in the perspective of the frontend, an MDX instruction
is sent to the cube and a hierarchical result set is
received by the cube... Even if the data is in a RDBMS...

Sumarizing: Doesn't matter if the cube is self-contained or
if the information is stored elsewhere, for the frontend
the storage is transparent because a MOLAP frontend ALWAYS
sends a MDX instruction to the cube and receives a
hierarchical result set...

I hope that helps...

Cheers!
Marcelo

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