Oracle Database creates server processes to handle the requests of user processes connected to an instance. A server process can be either of the following:. Your database is always enabled to allow dedicated server processes, but you must specifically configure and enable shared server by setting one or more initialization parameters. Figure , "Oracle Database Dedicated Server Processes" illustrates how dedicated server processes work. In this diagram two user processes are connected to the database through dedicated server processes. In general, it is better to be connected through a dispatcher and use a shared server process. A shared server process can be more efficient because it keeps the number of processes required for the running instance low. In the following situations, however, users and administrators should explicitly connect to an instance using a dedicated server process:. To submit a batch job for example, when a job can allow little or no idle time for the server process. To request a dedicated server connection when Oracle Database is configured for shared server, users must connect using a net service name that is configured to use a dedicated server.
Enabling Session Multiplexing
When client load causes a strain on memory and other system resources, database administrators can alleviate load issues by starting shared server resources. The shared server architecture enables a database server to allow many client processes to share very few server processes, so the number of users that can be supported is increased. With the shared server architecture, many client processes connect to a dispatcher. The dispatcher directs multiple incoming network session requests to a common queue. An idle shared server process from a shared pool of server processes picks up a request from the queue.
Dedicated Server Processes
The server process is not shared by any other client. PMON registers information about dedicated server processes with the listener. This enables the listener to start a dedicated server process when a client request arrives and forward the request to it. The following two figures show the basic difference between the shared server connection model and the traditional dedicated server connection model. In the shared server model, a dispatcher can support multiple client connections concurrently. In the dedicated server model, there is one server process for each client. Each time a connection request is received, a server process is started and dedicated to that connection until completed. This introduces a processing delay. Marketing Advertising Analytics Email.
This chapter discusses the processes in an Oracle database system and the different configurations available for an Oracle system. All connected Oracle users must run two modules of code to access an Oracle database instance. Oracle database server code: Each user has some Oracle database code executing on his or her behalf, which interprets and processes the application's SQL statements. These code modules are run by processes. A process is a "thread of control" or a mechanism in an operating system that can run a series of steps. Some operating systems use the terms job or task.