On 6/2/07, Allen Gilliland <[EMAIL PROTECTED]> wrote:
That looks really complicated. what's the purpose of the diagram? to
show the general relationships or to try and be a comprehensive diagram
of the entire data model?
IMO doing a comprehensive diagram is somewhat useless. It's hard to
maintain and keep up to date and ultimately a decent programmer should
be able to read the sql schema and understand it, it's not that
complicated. On the other hand a basic diagram which is meant to show
the relationships can be useful and likely can be made in such a way
that it doesn't have to be changed very often, so that's what I would
aim for. In specific I would ...
I totally disagree. Having all the relationships and fields on one
diagram is extremely useful for somebody trying to understand he data
model.
You are right that it is definitely difficult to maintain. And I do
agree that our data model is at the point where a comprehensive data
model diagram that fits on one 8x11 inch page is no longer going to be
possible.
* not put all the table columns, just put a few of the most important
ones and use "..." to indicate there are more columns in the table.
* spread things out a bit to organize things better visually and show
the most important relationships.
* try and group related components together, such as the pings tables.
* move all of the standalone tables off to one side.
In general, I agree with each of those ideas.
To explain the data model in a dev guide you'd want to have separate
diagrams. First you'd want one that shows relationships and
cardinalities, but not all of the fields. Then you'd probably want a
diagram with all of the fields for each part of the model you are
trying to explain.
I'll probably end up doing that if I write in detail about the data
model. But even with that, having a comprehensive data model to hang
on the wall is still useful. That's why the data model guy always has
such a big printer.
Any comments on content? Missing fields. Relationships?
- Dave
