Take two data models that represent two different data systems and place them next to each other. You may label them “Information Silo 1” and “Information Silo 2”. Within each designed information silo data model, there exists data entities connected by data entity relationships, which, when each data model is database instantiated and populated with data values, will each form a consistent database of data values. However, being information silos, there is no designed data entity relationships between silos, and as such, the data from one silo may never be reliably joined to data from the other silo.
To “integrate” the data from the two information silos, we now design a third data model for the purposes of integrating the data which we will label Operational Data Store (ODS). Now database instantiate the normalized ODS database. Copy the data from both information silos and transform that data into a form consistent with the ODS database and load the data values into the ODS database. We now have a consolidated set of consistent data, which by the way is itself isolated from the two information silos!
So, now we have proven that the data values from both information silos may be integrated. My question is, “What is wrong with the original information silos’ data models”? Is the ODS data model a better data model? When you add information silos 3, 4, and 5, the ODS now needs major enhancements. The ODS is no better designed than the original silos! Does this remind you of the fun game called “Whack a mole”?
Anyway, returning to the original two data models, I bet you will find some commonality between these two data models. Perhaps both data models contain customers, or addresses, or products, or financial information, or dates. This unrecognized commonality is the basis for integrating the data from the information silos into the ODS.
Therefore, the problem is that established data model methodologies do not recognize the commonality that normally exists between data models and therefore, every data model forms an information silo or sometimes an ODS of disparate data.