Having used relational databases for about 10 years, I decided to take
an SAP course because I wanted to explore the idea of the star schema.
Weight was added to my interest when I learned SAP is the 4th largest
software company in the world. Further weight was added when everyone
I talked to said the pay was excellent.

Now I wish I had not paid for this course.

I am finding this very uncomfortable. I dont think the concepts are
clear and I think SAP is a rather rigid product. And I dont enjoy
trying to shoe-horn all the data in a warehouse into a central fact
table with several dimension tables. Of course the dimension tables
point to master data in the extended star schema, but that is a
performance enhancement.

I find the relational approach intuitive and flexible. The one
drawback that my co-workers cite is that you can get lots and lots of
tables. My counter to this is that as long as the tables have a nice
accurate UML diagram (can anyone recommend a tool for this sort of
modelling? preferably free) then you should be able to follow it with
ease.

On May 10, 11:26*am, metaperl <metap... (AT) gmail (DOT) com> wrote:

Let me be more concrete. An InfoCube (database) in SAP can have a
central fact table and 13 user-defined dimension tables relating to
it. You get a lot of automatic queries/reports generated for you by
adapting your data to this module. Not only that, but SAP comes with
time and unit (of measure) dimensions automatically. You can get
timestamping/tracking of data quite easily.

But why only 13 user-defined tables? You might end up stacking tons of
characteristics (attributes in dimensions tables) into a single
dimension table just to keep under 13.

If not that, then you might be forced to create a different InfoCube
and then create multicubes.

metaperl wrote on 10.05.2009 17:26:
You might want to try Power*Architect. It's a free and OpenSource ER Modeller
which is quite nice.

Note that you are looking for an ER (Entity Relationship) modelling tool, *not*
an UML tool.

Thomas

On May 10, 11:52*am, Thomas Kellerer <FJIFALSDG... (AT) spammotel (DOT) com>
wrote:


I'm eager to check it out.

OK, but evidently UML notation allows for database schema design:
http://search.cpan.org/dist/DBIx-Dat...el.pm#SYNOPSIS

This Perl library uses UML notation to describe the database entities
which then get created in the database, along with accessors from
Perl.


Also note: http://argouml-db.tigris.org/documen.../UML_Model.htm

Argo UML allows for "UML database modelling"