OBIEE 11g : Basics of Physical Layer

Physical Layer is the first one from right and it also come first even when we are designing the RPD. It holds the information about the tables, columns, datatypes, database properties, connection pools etc

This is the exact replica of underlying Data source as we import the metadata from the database as shown below



This picture contains

• One database “Oracle Data Warehouse ” 
• Three connection pools 
• One Catalog
• One Database Schema “dbo”
• And 3 tables & four Aliases

Database

When we import some table or any metadata into the repository a Database icon will be created automatically which by default stores some of the important information associated with underlying data source. The below pictures gives you some idea about the same




Connection Pool

A connection pool is an object under a database, it stores the parameters or has the location where the parameters are available, using which we can connect to the database. As discussed earlier we require 5 parameters to connect to a Oracle Database. The picture will give you the insights of the same




Catalog

Catalog is just a folder in physical layer which doesn’t have any specific significance

Schema Name

Schema Name is the name of database object under which the table is stored. Generally these names will be same as the user names if manually created and will have different names when created using an application or creation utility.

Tables

Tables are the physical objects of database where the data is stored and are exact resemblance to the database object.

Alias

Alias is a duplicate of a table created when there is a need for the same physical table more than once, below are general cases where aliases are created

• Dimensions and facts are in same physical table
• Same physical table needs to be joined to another table more than once using different join conditions
• Improve performance by avoiding circular joins