Find me the attribute!……….. What attribute?

An attribute with a context is a meaningless attribute. (Even if it has a definition associated with it).

One of the interesting phases in ETL is the data mapping exercise. By the time data-mapping phase starts the target model and source model is already defined. But sometimes a report or excel file is pulled out by a user just like magician pulls a rabbit from the hat.  And declare it as a target. They will ask for the data to be mapped from the source. There is not target data model.

Probably the first thing will be to identify the list of attributes from the target and then off you go finding them in various source systems. Is this the right approach? Absolutely not! Will it work? Probably yes, but at the cost of time, money, resources and lots of unnecessary confusion. Why?

Lets take an example…. User wants to see qty of products sold by the Sales Representative (SR)…DATE, QUANTITY, PRICE , etc…

Is Sales Representative a person or a group of people?
Is ‘DATE’ Date of order, date of execution or date of shipping?
Is ‘QUANTITY’ qty of order, qty of execution or qty of shipping, also do we consider for qty of return?

Is ‘PRICE’ price of Order, price of actual execution or price of invoice?

Point is a floating data element is meaningless without the context of subject area or entity. The Attribute might itself be a combination of many other attributes from many other entities

So what the right approach?
Define a data model for target even if it is not an actual database. It will help you understand the entities to which it belongs. Then it will be easy to find similar entity/s in the source and map it to the target element.  

In short build a data-model. Before actually building start mapping the data.

Conclusion:  A attribute has no meaning unless it is attached to an entity.


Leave a Reply