Unit of time

One of the most important considerations in designing the data for the analytical database is to make sure that the unit of time over which the data is measured is appropriate to the data.

For example, measuring monthly sales by the second does not make any sense. Conversely measuring the changes in the Dow Jones Industrial average by the year is not terribly useful for most purposes.

When the data that is to be used for analytical purposes is designed, the unit of time over which the data is gathered and stored needs to be in synch with the data itself.