Data Modelling: The Thin Model [Entities with only identifiers]

Data Modelling: The Thin Model by Mark Needham.

From the post:

About a third of the way through Mastering Data Modeling the authors describe common data modelling mistakes and one in particular resonated with me – ‘Thin LDS, Lost Users‘.

LDS stands for ‘Logical Data Structure’ which is a diagram depicting what kinds of data some person or group wants to remember. In other words, a tool to help derive the conceptual model for our domain.

They describe the problem that a thin model can cause as follows:

[…] within 30 minutes [of the modelling session] the users were lost…we determined that the model was too thin. That is, many entities had just identifying descriptors.

While this is syntactically okay, when we revisited those entities asking, What else is memorable here? the users had lots to say.

When there was flesh on the bones, the uncertainty abated and the session took a positive course.

I found myself making the same mistake a couple of weeks ago during a graph modelling session. I tend to spend the majority of the time focused on the relationships between the bits of data and treat the meta data or attributes almost as an after thought.

A good example of why subjects need multiple attributes, even multiple identifying attributes.

When sketching just a bare data model, the author, having prepared in advance is conversant with the scant identifiers. The audience, on the other hand is not. Additional attributes for each entity quickly reminds the audience of the entity in question.

Take this as anecdotal evidence that multiple attributes assist users in recognition of entities (aka subjects).

Will that impact how you identify subjects for your users?

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