Oracle 参数 DISPATCHERS 官方解释，作用，如何配置最优化建议

本站中文解释

DISPATCHERS 参数定义了Oracle数据库运行时处理不同类型连接请求的监听进程。比如当客户机要建立I/O连接时，它会被路由到指定的进程上。

正确设置DISPATCHERS参数的方法是：

1. 首先，根据系统的资源能力来设置DISPATCHERS参数，尽量减少系统的开销。

2. 其次，可以根据对不同连接请求的优先级来设置DISPATCHERS参数。比如可以给当前的I/O连接请求设置更高的优先级，以确保数据库性能的最优。

3. 再次，在设置DISPATCHERS参数时要考虑到系统的连接能力。如果客户要处理很多请求，就要考虑增大DISPATCHERS参数，以支持更多的连接请求。

4. 最后，如果系统中出现了经常性的bottleneck，就需要重新调整DISPATCHERS参数，以弥补瓶颈。

官方英文解释

DISPATCHERS configures dispatcher processes in the shared server architecture.

The parsing software supports a name-value syntax to enable the specification of attributes in a position-independent, case-insensitive manner. For example:

Copy

    DISPATCHERS = '(PROTOCOL=TCP)(DISPATCHERS=3)'

   

Attributes may be specified using the full attribute name or any substring beginning with the first 3 characters. For example, SESSIONS can be specified as SES, SESS, SESSI, and so on.

Specify only one of the following attributes: PROTOCOL, ADDRESS, or DESCRIPTION. If you specify either ADDRESS or DESCRIPTION, then you can specify additional network attributes. Doing so supports multi-homed hosts.

dispatch_clause

• PROTOCOL

  The network protocol for which the dispatcher generates a listening endpoint.

• ADDRESS

  The network protocol address of the endpoint on which the dispatchers listen.

• DESCRIPTION

  The network description of the endpoint on which the dispatchers listen, including the protocol address.

options_clause

• DISPATCHERS

  The initial number of dispatchers to start. The default is 1.

• SESSIONS

  The maximum number of network sessions to allow for each dispatcher. The default is operating system-specific. Most operating systems have a default of 16 KB.

• CONNECTIONS

  The maximum number of network connections to allow for each dispatcher. The default is operating system-specific.

• MULTIPLEX

  Enables the Oracle Connection Manager session multiplexing feature.

  • The values 1, ON, YES, TRUE, and BOTH indicate that Network Session Multiplex is enabled for both incoming and outgoing network connections.

  • The value IN indicates that Network Session Multiplex is enabled for incoming network connections.

  • The value OUT indicates that Network Session Multiplexing is enabled for outgoing network connections.

  • The values 0, NO, OFF, and FALSE indicate that Network Session Multiplexing is disabled for both incoming and outgoing network connections. This is the default.

• LISTENER

  Specifies the network name of an address or address list of the Oracle Net listeners with which the dispatchers will register.

  The LISTENER attribute facilitates administration of multi-homed hosts. This attribute specifies the appropriate listeners with which the dispatchers will register. The LISTENER attribute takes precedence over the LOCAL_LISTENER and REMOTE_LISTENER parameters. See “LOCAL_LISTENER” and “REMOTE_LISTENER”.

• SERVICE

  Specifies one or more names by which clients can connect to the dispatchers. The SERVICE attribute takes precedence over any settings configured by using the SRVCTL command-line utility, the GDSCTL command-line utility, or the DBMS_SERVICE PL/SQL package.

• INDEX

  Use this attribute in an ALTER SYSTEM SET DISPATCHERS statement to indicate which dispatcher configuration you want to modify. (If you specify INDEX in the initialization parameter file, the Oracle Database ignores it.) In an ALTER SYSTEM statement, INDEX specifies the order in which the parameter’s values were initialized. The value ranges from 0 (for the first dispatcher configuration) to one less than the total number of dispatcher configurations you define.

  For example, if you specify 3 dispatcher configurations in the initialization parameter file, you would modify the third dispatcher configuration by specifying INDEX=2 in the ALTER SYSTEM statement. You could also add another dispatcher configuration in the ALTER SYSTEM statement by specifying INDEX=3.

  If INDEX is not specified in the ALTER SYSTEM statement, then the PROTOCOL, ADDRESS, or DESCRIPTION attributes must be specified, and if a dispatcher configuration matching this PROTOCOL, ADDRESS, or DESCRIPTION exists, then that configuration will be modified. Otherwise, a new configuration will be added.

See Also:

• “SHARED_SERVERS”

• Oracle Database Net
  Services Administrator’s Guide and Oracle Database
  Administrator’s Guide for more information on setting this parameter