You use the ALTER SERVER statement to modify a server definition. Some of the information within a server definition is stored as server options. When you modify a server definition, it is important to understand the options that you can specify about the server.
A server definition identifies a data source to the federated database. The server definition consists of a local name and other information about that data source server. The server definition is used by the wrapper when SQL statements that use nicknames are submitted to the federated database.
For relational data sources, server options can be set temporarily using the SET SERVER OPTION statement. This statement overrides the server option value in the server definition for the duration of a single connection to the federated database. For static SQL, using the SET SERVER OPTION statement affects only the execution of the static SQL statement. Using the SET SERVER OPTION statement has no affect on the plans that the optimize generates.