Why Heterogeneous?

[vueman00]

Hi,

I am a fresh student and I am trying to understand the Heterogeneous concept. I am wondering what the difference is between a Heterogenous schema and a regular schema. Why would someone use a heterogeneous vs a regular schema and when is it appropriate to use one or the other?

Thanks much for your input.

Vue

[BoxesAndLines]

Heterogenous normally refers to different sources for the same class of information. For example, most companies have multiple channels for managing customers. Each of those siloed applications will have their own interpretation of the data model and underlying data structures. In the EDW, I need to reconcile the heterogenous sources to present a consistent, unified, view of the customer.

[vueman00]

would this be the same as Snowflaking?

[ngalemmo]

No. Snowflaking is a form of star schema where a dimension table contains a foreign key to another dimension table. That is all the term means.

I've never used the term 'heterogeneous' when describing a data warehouse schema... it would seem to me such an approach (i.e. a heterogeneous data warehouse) would be counter-productive, as one of the goals of DW design is to integrate heterogeneous sources, rather than keep them that way.

[ngalemmo]

To carry this discussion a bit further, take an example of a company that has separate product lines within separate divisions with separate sales systems (orders, product master, customer master, inventory, etc...).

These sources are heterogeneous... different data, different data structures and so forth, but they both cover 'sales' from a corporate point of view. In a well designed data warehouse, these sources would be integrated such that data can be viewed and analyzed seamlessly across divisions using standard as well as divisional interpretations, yet at the same time, retain the identity and nomenclature of the source systems.

My guess is, a heterogeneous data warehouse model would keep everything separate, not attempt to conform data interpretation and leave it up to the users to figure out how to combine the data. Not a very productive environment...

[vueman00]

Thanks for the clarification. I appreciate it!

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