My skin is understood
Entity refers to the usual dimension we usually say. The fact is that the value fields in the fact that we usually say (I didn't understand why I can't collect the facts directly in the report) entity, the fact is the field directly corresponding to the database table, which belongs to the frame object (Schema Object). Metrics are what we usually say. Metrics can be operated by entities and facts.
Why define the fact that the fact is defined first? This is also the powerful factor of MSTR modeling. The fact is the framework object, which is modeled, and the metric is a common object, which is a design work. Imagine that a facts can define a fact that a lot of metrics can be defined, such as the last month's income (plus transformation), a type of customer's income (plus condition), annual income (plus level), can also be more Many composite metrics. If you direct the metrics directly on the field, you will collect the table field in each metric, which is less realistic for the designer (the facts block the data warehouse physical structure). Also, if your income field is changed slightly (such as the field name modified, or add a new income table), you only need to modify the corresponding fact, do not need to update all metrics so that the maintenance cost is minimized.
