You can design a DataServer application that emphasizes portability across data sources or one that optimizes the strengths of the DataServer's interaction with a particular aspect of the Oracle RDBMS. For example, you can write a query that gives you consistent results across databases or that takes advantage of Oracle's cursor management.

In addition to influencing how DataServer applications perform through queries, you can control how the DataServer processes queries on a statement-by-statement basis. Some of the DataServer's default behavior might not be optimal for the application you are designing. The QUERY-TUNING phrase and startup and connection parameters give you the ability to control query processing. In addition to reading the following sections, see Query tuning with connection and startup parameters for information on tuning queries at compile time and run time. See Sample Queries for examples of how the DataServer handles queries with and without query-tuning options.