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Exercise No. 50: Getting Mails (dfm)

The following E/R schema is about getting mails.

A user who is of a certain type gets a mail. The mail is delivered by an Internet Service Provider (ISP) and may be encrypted; this encryption is of a certain encryption standard. The mail itself is of a certain type and belongs to a certain group (parallel hierarchy). The time dimension consists of month and quarter.

Figure D.E.42.1 - getting mails

Please identify the fact of interest and build the attribute tree. Some of the attributes of a mail are not of interest for our data warehouse: sender and body can be neglected. We will only classify mails by an encryption standard. Some attributes cannot be used for aggregation in a meaningful way. Those 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 two additional fact attributes; one counting the number of gets, and one counting the number of users.

Solution

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