Forum .LRN Q&A: Datawarehousing at dotLRN

Posted by Pablo Contreras on
Hi everybody I istalled dotlrn and all is fine, but I need to find out if dotlrn has an Multidimentional MOdel. As you can see dotlrn has a such number of packages but I want to know where the data is defined the following things:
1. Data operational.
2. Datamart.
3. Multidimentional Model (in this point I need to know what data is modeling at this model using star and snowflake scheme).
4. Cubo Model.
5. ETL.

Anybody can help me?

Posted by Carl Robert Blesius on
I do not really understand your post or question(s) Pablo, but I did find a good reference on Multidimensional DB technology that helped a little

Based on this document I think the underlying data model in .LRN has little to do with "Cubo Models" or "Multiple Dimensions".

Here is snipit from the document:

Using a Structured Query Language database management
system offers considerable flexibility in structuring
data. However, formulating many desirable
computations such as cumulative aggregates (sales in
year to date), combining totals and subtotals, or determining
rankings such as the top 10 selling products is
difficult if not impossible in standard SQL. Also, transposing
rows and columns requires manually specifying
and combining multiple views. Although SQL
extensions such as the data cube operator3 and query
windows4 will remedy some of these problems, the
SQL-based relational model does not handle hierarchical
dimensions satisfactorily

We use SQL around here.

Posted by melina dee on
thanx for sharing the information about the Multidimensional DB technology and then script of the document
Posted by Eduardo Santos on
Hi Pablo,

If you really understand Data Warehouse, you'll see that part of the problem is to find out what is the data you are going to need. The fact is that there's no such thing as a Data Warehouse model for dotLRN. It depends ont he data you want to gatherm and what kind of relations you want to monitor.

The first task is to understand the relations under OpenACS, I mean, how the objects are related to each other. You will realize that we have a great advantage: the metadata system. You'll see that there's a lot of data you can gather, and use this to build up your datamarts.

After that, you can create your Multidimensional model, considering whatever technology you want to use. OpenACS basically uses a relational database, based on objects. A good tip for dimensions is to choose wich objects you want to measure, I mean, wich ones you are going to see as a dimension, and then build your multidimensional model.

If you get into this part, building the cubs (cubos) can be very easy: you only have to know how you want to see the relations with each other.

As you have the data you need, just choose the ETL tools of your preference to extract the data. Pentaho has a very good suit for BI (, wich is basically Open Source, but you can choose whatever you want, even SQL scripts, to extract the data.

This subject is slightly related to my research right now, and let me know if I can hep you somehow.

Best regards