oracle net service

The potential benefits of shared server are as follows:

• Reduces the number of processes on the operating system

  A small number of shared servers can perform the same amount of processing as many dedicated servers.

• Reduces instance PGA memory

  Every dedicated or shared server has a PGA. Fewer server processes means fewer PGAs and less process management.

• Increases application scalability and the number of clients that can simultaneously connect to the database

• May be faster than dedicated server when the rate of client connections and disconnections is high

Shared server has several disadvantages, including slower response time in some cases, incomplete feature support, and increased complexity for setup and tuning.

Note:

To use shared servers, a client process must connect through Oracle Net Services, even if the process runs on the same computer as the Oracle Database instance.

 

Note:

Each client process that connects to a dispatcher must use Oracle Net Services, even if both processes run on the same host.

All session-related information is contained in the SGA. Each shared server process must be able to access all sessions' data spaces so that any server can handle requests from any session. Space is allocated in the SGA for each session's data space.

Certain administrative activities cannot be performed while connected to a dispatcher process, including shutting down or starting an instance and media recovery. These activities are typically performed when connected with administrator privileges. To connect with administrator privileges in a system configured with shared servers, you must specify that you want to use a dedicated server process.

Database Resident Connection Pooling (DRCP) provides a connection pool of dedicated servers for typical Web application scenarios. A Web application typically makes a database connection, uses the connection briefly, and then releases it. Through DRCP, the database can scale to tens of thousands of simultaneous connections.

• Complements middle-tier connection pools that share connections between threads in a middle-tier process.

• Enables database connections to be shared across multiple middle-tier processes. These middle-tier processes may belong to the same or different middle-tier host.

• Enables a significant reduction in key database resources required to support many client connections. For example, DRCP reduces the memory required for the database and boosts the scalability of the database and middle tier. The pool of available servers also reduces the cost of re-creating client connections.

• Provides pooling for architectures with multi-process, single-threaded application servers, such as PHP and Apache, that cannot do middle-tier connection pooling.