In the phase of analysis of requirement, it must collect and leak what the single customers of the Datamart expect or could expect from the same one.
Like saying, this phase is fruit of the conversations had with the responsibles of the Plan of Virtual Warehouse; sure a deepened analysis more would be possible if the MV in its real operational behavior were analyzed.

The choice of the facts, that is the concepts of primary interest for the analysis of the system of support to the decisions, is essentially one chosen of the final customer. For every fact it must define the history interval, that is which temporal arc will have to embrace the events memoryzation.

Once it identifies the facts to you, granularità must choose the level of detail () that better they represent them.
This last choice is important in order to determine the speed of answer of the system (elevated to low level of detail) and level of detail, that is deepened how much must be our analysis.
As a result of this first analysis, and considering outline ER of the database of departure, has been characterizes these facts to you thought important for the system.

Fact	Possible Dimensions	Possible Measures	Storicità
Supplyes	product, date, magazzino_scorta, positioning	amount to warehouse	5 years
Purchases	product, date, magazzino_acquirente, positioning	sold amount, amount	5 years
Deliveries	bubble, data_consegna, conveyor, luogo_partenza, luogo_arrivo	lead Time	2 years

During this phase it must calculate also the workload, expressed in natural language; it is much profit in order to understand which level of soluble to use in the Datamart.

Fact	Interrogation
Supplyes	Which produced has been had supply made unusable in the last trimester? Of which products the sottoscorta has been had more often in the last month Course weekly magazine of the supplyes for produced determining. To establish the consumption habits ages them Which products come use you little (are from the customer that give all the District); servants in order to decide the reduction of the supplyes etc.
Purchases	Which products it has been more often acquired in the last period of two months? Which amount of produced determining it has been sold in the last year? In which zone of the District the greater need of a determined type of product has been had? etc
Deliveries	Which it is the average speed of delivery of a determined conveyor in the last week on the covered determined one? And in the last month? Which is the conveyor with lead Time more low on the covered determined one? Which is the faster distance between X and Y? etc

That some attributes, which product or warehouse, in common to two or more are pointed out. They go flavored themselves entire, and inserted in all and the three hierarchies of the facts.
It could be interesting, in a second phase of development of the MV, in which the MV it becomes outsourcer, to establish the quality of the performances of the suppliers accustoms them; it would have therefore to add an ulterior fact, that is the supply, that it has for meter of appraisal, lead Time of supply, rendered and quality supplied assets.
Or as made additional us it could be the satisfaction of the customer, that is to understand how many times and like the customer of the MV it has carried out of the demands that they have not found matches of availability in the District, or how many times the demands have been inevase, for problems in several the passages (as an example breach of means of transport or strike of the workers of the yielding warehouse).