As analytic system, normally TM1 data source come from ERP system which is (mostly) Relational Database, and usually it has so many tables.
Someone who understands the data structure may know all about the structure data in ERP database, and it should be easier for him/her to retrieve the data and send it to TM1 system as data source.
But, mostly the team members who implement Cognos TM1 are the different people who does not involve in ERP system development or implementation.
We can ask for flat file to become Cognos TM1 datasource. Meaning there is a system (or manually by someone) which generate the flat files and put it in a specific folder. Easy! And we do not need to know anything behind how and why the data generated, correct or wrong. Problem comes when users reported data wrong and usually they think that it might be system error ,
Then we just refer to the data source and show them the fact according to data provided.
How if the data source comes from relational database, online to the ERP system? It should be same. Even though the relational database is a big database with so many tables, but we should see only the structure that we have defined as Cognos TM1 datasource (and actually this concept should same to all systems). It is same with the flat file datasource concept. The key is to make the data source as “view” with structure as we already defined. It is still online data source, but we don’t need to see the whole database. We just need access right from database admin to access the “view”, and usually we just need “read” access since you can’t do “write” to that database. (Veronika Rotua Gultom)
Veronika Rotua Gultom 