Wikka Logical Data Model

On this page I present a (half-way) logical data model for Wikka's data: an explanation of how the data "works" and a step on the way towards a better and expanded database.

Explaining the model to myself

On the WikkaPhysicalDataModel page I explained how I set out to make a model of the (current) physical data structure in Wikka's database and found I could not model all the relationships between the tables because the database is actually not structured to directly support the relationships that logically do exist between the data.

So in parallel with creating the physical model, I created a logical one as well by "pulling apart" some tables that logically should be separate but (for unknown reasons) are not now. Adding some keys, and a field, and enlarging a few others, soon gave me a much better "picture" of how Wikka's data all hangs together.

The (sort of) logical data model

Actually it's not merely a logical data model - with the detail there is, it actually looks like a physical data model, only somewhat different than the current one. This is intentional: compared to the current physical model it's hypothetical (and hopefully clarifying) but at the same time this intended as a proposal for a future direction for our database. In my opinion this structure would not only be "cleaner" but would also support future expansion with new data types (tables) better. So here is a (slightly reduced) image of the
"logical" data model. In the downloads section below you'll find a download link for the full-size image.

logical model of Wikka's database showing the proposed tables and their relationships


You can also download a
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full-size version of the image.

If you're interested in a more detailed look at the model, you can download
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the XML file with the model that you can load into DB Designer 4: it's a free application that is available for Windows and Linux, and released under GPL: well worth a look.


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