While entity-relationship diagramming has traditionally been associated with highly normalized models such as online transaction processing (OLTP) applications, the technique is still useful in dimensional modeling. You can create the logical design using a pen and paper, or you can use a design tool such as Oracle Warehouse Builder or Oracle Designer. In relational databases, an attribute maps to a column. An attribute is a component of an entity and helps define the uniqueness of the entity. In relational databases, an entity often maps to a table.
An entity represents a chunk of information.
GIDEROS SET LOGICAL DIMENSION SERIES
The process of logical design involves arranging data into a series of logical relationships called entities and attributes. You do not deal with the physical implementation details yet you deal only with defining the types of information that you need. A well-planned design allows for growth and changes as the needs of users change and evolve.īy beginning with the logical design, you focus on the information requirements without getting bogged down immediately with implementation detail.Ī logical design is a conceptual, abstract design. Your design is driven primarily by end-user utility, but the end users may not know what they need until they see it. End users typically want to perform analysis and look at aggregated data, rather than at individual transactions. Your design should be oriented toward the needs of the end users. In the physical design, you look at the most effective way of storing and retrieving the objects. In the logical design, you look at the logical relationships among the objects. The logical design is more conceptual and abstract than the physical design. In this step, you create the logical and physical design for the data warehouse and, in the process, define the specific data content, relationships within and between groups of data, the system environment supporting your data warehouse, the data transformations required, and the frequency with which data is refreshed. So now you need to translate your requirements into a system deliverable. Moreover, it is likely that the business requirements are already defined, the scope of your application has been agreed upon, and you have a conceptual design.
If you are reading this guide, it is likely that your organization has already decided to build a data warehouse.
GIDEROS SET LOGICAL DIMENSION HOW TO
This chapter tells how to design a data warehousing environment, and includes the following topics:
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