Server definitions and server options
After wrappers are created for the data sources, the federated instance owner defines the data sources to the federated database.
- The type and version of the data source
- The database name for the data source (RDBMS only)
- Metadata that is specific to the data source
For example, a Db2® database family data source can have multiple databases. The definition must specify which database the federated server can connect to. In contrast, an Oracle data source has one database, and the federated server can connect to the database without knowing its name. The database name is not included in the federated server definition of an Oracle data source.
The name and other information that the instance owner supplies to the federated server are collectively called a server definition. Data sources answer requests for data and are servers in their own right.
The CREATE SERVER and ALTER SERVER statements are used to create and modify a server definition.
Some of the information within a server definition is stored as server options. When you create server definitions, it is important to understand the options that you can specify about the server.
Server options can be set to persist over successive connections to the data source, or set for the duration of a single connection.