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Exercise No. 26: Project Management (dfm)

This simplified E/R schema shows a project managemant case.

The project for a customer is split up to various work packages and always one person is responsible for the completion of the task. It is taken care of in a certain location.
The time dimension consists of day, month and year.

Figure D.E.53.1 - project management

Please identify the fact of interest and build the attribute tree. Attributes that cannot be used for aggregation in a meaningful way should be tagged as non-dimension attributes in the fact schema.

Then derive the fact schema from the tree by defining dimensions, fact attributes and hierarchies and build a glossary for the fact attributes if there are any.

Please include an additional fact attribute counting the number of work packages.

Solution

Entity WORK PACKAGE is chosen as the only fact. Its identifier becomes the root of the attribute tree. All other attributes or identifiers become nodes.

Figure D.E.53.2 - The attribute tree

Project, location and person responsible are defined as dimensions and the dimension day is introduced as a range of the date attribute. The attribute costs becomes a fact attribute and number of packages is added.

The phone number of the customer cannot be used for aggregation and is tagged as non-dimension attribute.

Figure D.E.53.3 - The fact schema

costs = SUM (WORK PACKAGE.costs)

no. of packages = COUNT (WORK PACKAGE)

This exercise is part of a case study: dfm - apa - log

Exercises List