Difference between OLAP cube and Universe

general discussion
1

Hey,

Where can i get the information of difference between OLAP cube and Universe?

Thanks.

Onn

onnonn (BOB member since 2003-11-03)

2

Aggregation!
An Olap cube is a prebuilt cube of data that has been aggregated according to pre-determined dimensions whereas a universe is a semantic layer over a set of joined tables that generates sql and aggregation on the fly depending what the user selects.
The measures can use sum / average etc and then the dimension objects will be aggregated at run time - taking longer but more flexible.
I’m sure there should be some BO docs on their site.

MikeD :south_africa: (BOB member since 2002-06-18)

3

Simpy put . . . an OLAP cube contains data; a universe doesn’t.

OLAP cube: Data
Universe: Meta Data

MichaelWelter :vatican_city: (BOB member since 2002-08-08)

4

And a universe can be built on top of an OLAP cube :wink:

Andreas :de: (BOB member since 2002-06-20)

5

Hi,

Thanks for your helpful answer.

Can i get some Advantage and disadvantage for using OLAP and Universe?

Thanks.

Onn

onnonn (BOB member since 2003-11-03)

6

It depends on your needs. Tell us about your requirements.

MichaelWelter :vatican_city: (BOB member since 2002-08-08)

7

Michael Welter,

I need to get some write-up about OLAP (MOLAP/ROLAP/HOLAP) vs BO Universe. My cases like: -

If my current user are using MOLAP, what are the beneficial part for user change from MOLAP to Universe (RDBMS)?

Thanks for help.

Onn

onnonn (BOB member since 2003-11-03)

8

A) OLAP cubes must be re-built if any changes occur. Universes based on a relational database are more flexible.

B) If you build universes on top of OLAP cubes (available with XI R2) your users will have the same interface when building reports independent of the data source (RDBMS or OLAP cube).

C) OLAP cubes usually do not provide data at the lowest grain (think part number for example) nor do OLAP cubes show operational/live data.

Keep in mind it is not so much about OLAP versus Universe, because a universe can now be built on top of an OLAP cube. It is more a question of OLAP versus Relational Database/Datamart.

Andreas :de: (BOB member since 2002-06-20)

9

Yes, we can develop universe on top of OLAP. but y do we do that.? What is the advantage on developing universe over OLAP?

Thanks,
JB

Jayabal :india: (BOB member since 2009-01-05)

10

Advantages, this:-

Designer guide, chapter 4, here:-
http://help.sap.com/businessobject/product_guides/boexir31/en/xi3-1_designer_en.pdf

Mak 1 :uk: (BOB member since 2005-01-06)

11

Resolving chasm traps and fan traps is all well and good, but chapter 6 on working with OLAP will be better. :yesnod:

dessa :madagascar: (BOB member since 2004-01-29)

12

MikeD :south_africa: (BOB member since 2002-06-18)

13

Des, I was never any good at numbers, they confuse me :rotf: .

Mak 1 :uk: (BOB member since 2005-01-06)

14

Depends on how you build your cube, ROLAP cubes can show live data.

zack :us: (BOB member since 2007-08-02)

15

Hang on - this isn’t the case of one against the other. OLAP (and mind you that OLAP doesn’t mean memory-based-cubes although that’s what people refer to nowadways) is a data storage strategy.

A BO Universe is a semantic layer, allowing users to construct data queries by dragging friendly named objects onto a report, shielding those users from the complexities of query languages like SQL or MDX.

Business Objects Web Intelligence, the most popular user-friendly, web-driven query tool :mrgreen: , uses this Universe to access data sources like OLAP cubes, relational databases, dimensional data warehouses etc.

Comparing an OLAP cube with a Business Objects Universe is comparing a pan and eggs - you need both to make a good omelette
:mrsbob:

ErikR :new_zealand: (BOB member since 2007-01-10)

16

Eric, Can I get a flat white, with that :stuck_out_tongue: ?

Mak 1 :uk: (BOB member since 2005-01-06)

17

In my opinion it is always a choice you need to make, depending on client wishes/needs. Is lightning speed very important, then OLAP cubes are the way to go (usually requiring more work, ie more expensive), otherwise normal reports based on a metadata layer are sufficient.

An additional bonus of OLAP cubes is that you can give users a way to freely analyse their data, searching for anomalies. Reports can feel like chains for users because the format is very fixed.

HenkK

HenkK :netherlands: (BOB member since 2004-03-02)

18

Has anyone on this board ever heard of a 3rd party tool that can use a BO Universe as a “middleman” to the underlying relational data source to build SSAS cubes that can be viewed with Voyager?

We have existing universes that query our data marts, which we use for detailed reporting. However, we want to move into the more analytical and “exploratory” area of reporting by using Voyager with OLAP cubes.

I know how to build cubes using SSAS, but unfortunately, SSAS does not allow us to leverage our existing universes. Whatever SQL is defined in the universe has to be re-coded in SSAS. Which means when business logic changes in the universe, we have to repeat the change in the OLAP project.

It would be nice if there was some kind of plug-in tool that accessed the underlying relational data via a BO universe to build cubes. That way we can leverage the universes and not have to worry about duplicating business logic.

We recently looked at SAP’s new Business Objects Explorer offering and it seems to try to do something like that, although the SAP reps won’t “admit” to this being a cube builder. (It seems to me that in the Business Objects world, “cube” is a dirty four-letter word.) But my company won’t buy Explorer because they already bought Voyager two years ago and their directive right now is “use what you’ve already got, don’t bug us for 50,000$ for Explorer licences.” (Which I agree with, it seems like SAP is trying to double-dip by splitting up their OLAP front-end offerings.)

datasmith :canada: (BOB member since 2006-11-07)