Subsetting a data model

[Former Member]

In ERwin when I needed to create a model that was a subset of a larger model, I could put everything I needed in one diagram and the use the "Derive model from Subject Area" feature.

I'm trying to do this with CDMs and LDMs in PowerDesigner (without a repository, I might add).  I need to create a subset model of the Corporate CDM (I'll be doing similar thing for LDM) for my project.  Re-use some pieces as-is and change and add-to other parts.  Then I submit it for review.  Once the model is accepted, it will be merged back into the Corporate model.

As I mentioned above, I used to do this all the time in ERwin.  I was a master of the ERwin Merge.

Now in PowerDesigner, I know they do things differently, but there must be a way to create a clean subset.  I have tried creating a Package within the model for the subset.  But I can't see a way forward from there.  And creating the package seems to have created (or highlighted?) issues with and inheritance that is now only partly inside the package.

I have to run to a meeting now.  I'll post more details later if I have time.

Any help appreciated.

Jane Roberts

[Former Member · Accepted solution]

If you've already got your subset in a package, you can use Tools | Generate Physical Data Model.  On the generation options, go to the 'Selection' tab.  At the top left, you'll see your model name.  Drop that down and you can select your package instead.  Choose the rest of your options and hit okay.  You'll get a model with just the objects in your package (you may get shortcuts for needed objects outside the package).  Best of luck.

[GeorgeMcGeachie · Accepted solution]

In the Selection tab during model generation, there is a button near the right-hand end of the toolbar that allows you to use the objects that you've currently got selected on your diagram to define the selection for generation.  That way, you don't need to worry about packages.

By the way, you do need to make sure that inheritances are owned by the same package as the parent entity to avoid issues. You can check them by creating a List report of inheritances, and including information from the parent entity (I'm working from memory here, so forgive me if you can't do that) .

If you need training, Toronto's weather seems fine to me .

[Former Member · Accepted solution]

Thanks.  This triggered my memory for what I need.  I can Generate a subset CDM from another CDM.  And use the selection options as you say. I don't know why I keep forgetting this.

[GeorgeMcGeachie · Accepted solution]

... don't forget that you save your selection set using the dialogue at the bottom of the screen, in case you want to repeat it (you can also access the selection set in a script if you want to know what's in it)