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About Server and Client Processes

In addition to background processes, Oracle Database crcates server processes that handle the connection rcquests of user or client processes. A user connection is composcd of the following distinct picces:

■A client program acting on behalf of the user, such as Oracle Enterprise Manager (Enterprise Manager), SQL*Plus, or an application

■A scrver process that handlcs the connection to the database on behalf of the client program, and that performs much of the work for the client program, such as parsing and running SQL statements, and retrieving and returning results to the client program

Server processes can be either dedicated or shared. When server processes are dedicated, Oracle Database is running in dedicated server modę. When server processes are shared. Oracle Database is running in shared server modę. In dedicated server modę. each client process has its own server process. Although a dedicated server process is good for long-running queries and administrative tasks, an idle process or too many dedicated processes can result in an inefficient use of resources. Using shared server modę eliminates the need for a dedicated server process for each user connection, requires less memory for each user connection, and enables morę users to access the database. Shared server modę is morę efficient at supporting multiple client programs making frequent short-running queries.