Sharepoint 2013 Reporting Services & OLAP Cubes for Data Modeling.

Question

I've been using PowerPivot & PowerView in Excel 2013 Pro for some time now so am now eager to get set up with Sharepoint 2013 Reporting Services.
Before set up Reporting Services  I have just one question to resolve.
What are the benefits/differences of using a normal flat table set up, compared to an OLAP cube?
Should I base my Data Model on an OLAP Cube or just Connect to tables in my SQL 2012 database?
I realize that OLAP Cubes aggregate data making it faster to return results, but am unclear if this is needed with Data Modeling for Sharepoint 2013.
Many thanks,
Mike

Answer 1

So yes, PV is an in-memory cube. When data is loaded from the data source, it's cached in memory, and stored (compressed) in the Excel file. (also, same concept for SSAS Tabular mode... loads from source, cached in mem, but also stored (compressed) in data
files, in the event that the server reboots, or something similar).
As far as performance, tabular uses memory, but has a shorter load process (no ETL, no cube processing)... OLAP/MDX uses less memory, by requiring ETL and cube processing... technically tabular uses column compression, so the memory consumption will be based
on the type of data (numeric data is GREAT, text not as much)... but the decision to use OLAP (MDX)/TAB (DAX) is just dependent on the type of load and your needs... both platforms CAN do realtime queries (ROLAP in multidimensional, or DirectQuery for tabular),
or can use their processed/in-memory cache (MOLAP in multidimensional, xVelocity for tabular) to process queries.
if you have a cube, there's no need to reinvent the wheel (especially since there's no way to convert/import the BIDS/SSDT project from MDX to DAX). If you have SSAS 2012 SP1 CU4 or later, you can connect PV (from Excel OR from within SP) directly to the
MDX cube.
Generally, the benefit of PP is for the power users who can build models quickly and easily (without needing to talk to the BI dept)... SharePoint lets those people share the reports with a team... if it's worthy of including in an enterprise warehouse,
it gets handed off to the BI folks who vet the process and calculations... but by that time, the business has received value from the self-service (Excel) and team (SharePoint) analytics... and the BI team has less effort since the PP model includes data sources
and calculations - aside from verifying the sources and calculations, BI can just port the effort into the existing enterprise ETL / warehouse / cubes / reports... shorter dev cycle.
I'll be speaking on this very topic (done so several times already) this weekend in Chicago at SharePoint Saturday!
http://www.spschicagosuburbs.com/Pages/Sessions.aspx
Scott Brickey
MCTS, MCPD, MCITP
www.sbrickey.com
Strategic Data Systems - for all your SharePoint needs