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PLANNING OF THE DATAWAREHOUSE FOR THE VIRTUAL WAREHOUSE

LOGICAL PLANNING

The multidimensional model on relational systems is based on the so-called outline to star (star outline) and on its varying.

It is composed gives:

  • with of relations DT1.....DTn, calls dimension table, every one correspondent to one dimension. Every DTi is characterized from a primary key of and from with of attributes that describe to the dimensions of analysis and the various levels of aggregation
  • a relation FT, call fact table, that it imports the keys of all the dimension table. The primary key of FT is given from with of the external keys of the dimension table
The multidimensional vision is obtained executing the association (join) between fact table and the dimension table.

The dimension table they are not in third normal shape, since the contemporary presence of all the attributes of a hierarchy gives place to dependencies works them transitive. This produces redundancies, but determined information allows to diminish the number of associations to make in order to obtain one.

In case space was wanted to be saved on disc or to follow the theory of the normalization, would have to introduce new tables and to create therefore one outline to snowflake.
In this job the redundancy has been maintained maximum.
Figure. Star Outline "Lying"


Figure. Star Outline "Acquires"


Figure. Star Outline "Deliveries"

PHYSICAL PLANNING

With the physical planning the choices completed are realized during are made of planning and the outline of the Datamart assumes its final shape.

In the first step of the physical planning the 2000 (MagazzinoVirtualeDataMart has been created database relational with SQL Server), to the same way of the created DataBase for MV (the MagazzinoVirtuale).



Once completed this passage, adopts a position database the relational MagazzinoVirtualeDataMart like source for the cubes on which carrying out the analysis through "Analysis the present Service "in the package of SQL Server 2000.
If the database it resides on Server SQL, then it must settarlo like origin give "Microsoft to you OLE DB Provider for SQL Server".

This the result for the cube of the purchases


Ditto for that one of the supplyes.

The result, in practical will be constituted gives of the cubes that are possible to be annoying in real time, to various levels of aggregation, in the time, the space, the product and therefore via, supplying of turns out you of easy access with interfaces user-friendly.

This type of navigation is not other that the first step towards one navigation of gives to you more much been left over.

 

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