Data Design
Before modeling the data and relationships, you should create a design. You should identify which data is used most frequently and the paths that are used to access the data. This information is required to define the optimal data model. This is not necessarily the ideal data model, because it might contain redundant data to better meet performance requirements.
User Views and Access Paths
A business activity often needs data from more than one modeled entity. The data needed is called a 'user view'. A business activity accesses the entities of the user view via 'access paths'. To retrieve the data needed, an access path uses the relationship between two associated entities or the dynamic link between two components.
Access paths therefore determine the number of tables that must be joined to retrieve the data needed. Retrieving data from joined tables causes the system load to be significantly larger than retrieving the same data from a single table.
Because long access paths increase the system load of the application, you need to analyze the access paths that constitute a user view, then use that information to design the optimal data model, one that minimizes the access paths.
