=====Wikka Logical Data Model=====

>>See also:
~-WikkaTableStructure
~-WikkaPhysicalDataModel
~-WikkaResources
>>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.

{{image src="images/models/logical_current_s.png" alt="logical model of Wikka's database showing the proposed tables and their relationships"}}

===Downloads===
You can also download a {{files download="logical_current_x.png" text="full-size version of the image"}}.

If you're interested in a more detailed look at the model, you can download {{files download="logical_current.xml" text="the XML file with the model"}} that you can load into **[[http://www.fabforce.net/dbdesigner4/ | DB Designer 4]]**: it's a free application that is available for Windows and Linux, and released under GPL: well worth a look.

--JavaWoman

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CategoryWikkaArchitecture