本站中文解释
CONNECTION_BROKERS参数定义集群中TNS监听器之间的可用状态跟踪保持器（Connection Broker）的总数。它是控制可用状态跟踪保持器的系统参数，也可以是服务的一部分，易于SQL语句更新。
CONNECTION_BROKERS 可以用来配置默认会话路由，这里指的是在Oracle Real Application Clusters (RAC) 环境下，当用户访问特定会话时，必须指定节点 upstream 或 downstream 方向会话路由将要去往的节点。此外，CONNECTION_BROKERS 也可以用来配置在客户端/服务器环境下，当用户访问特定会话时，必须指定特定节点访问数据库会话负载均衡流量上行或下行到服务器。
正确设置CONNECTION_BROKERS参数需要根据当前环境来进行，一般情况下可以设置为预分配的最大值。
官方英文解释
CONNECTION_BROKERS is used to specify connection broker types, the number of connection brokers of each type, and the maximum number of connections per broker.
| Property | Description |
|---|---|
|
Parameter type |
String |
|
Syntax |
|
|
Syntax |
broker_description::=
|
|
Syntax |
type_clause::=
Indicates the broker type. This is a mandatory parameter. |
|
Syntax |
brokers_clause::=
Indicates the number of brokers of the specified type. This is a mandatory parameter. The specified integer value must be greater than or equal to 0. If set to 0, brokers will not accept new connections, but existing connections will continue as normal. |
|
Syntax |
broker_options::=
The maximum number of connections per broker. This is an optional parameter. If the specified integer value is greater than the maximum allowed for the platform, the maximum allowed for the platform is used. |
|
Default value |
The default value for the initialization parameter will contain the |
|
Modifiable |
|
|
Modifiable in a PDB |
No |
|
Basic |
No |
|
Oracle RAC |
The same value should be set on all instances |
The connection brokers are used in these cases:
-
DEDICATED brokers are used by the multiprocess and multithreaded Oracle features. See Oracle Database
Concepts for more information about these features.DEDICATEDbrokers are also used when theUSE_DEDICATED_BROKERinitialization parameter is set totrue. See “USE_DEDICATED_BROKER” for more information about theUSE_DEDICATED_BROKERinitialization parameter. -
EMON brokers are used when there is a client registered for notification over 12c AQ queues. It is not on by default. See Oracle Database Advanced
Queuing User’s Guide for more information about AQ queues. -
POOLED brokers are used whenever a Database Resident Connection Pooling (DRCP) pool is active. See Oracle Database
Concepts for more information about DRCP pooling.The POOLED broker does not appear in the parameter by default. In this case, the DRCP fields are used. If you specify the
POOLEDbroker in the parameter, then that specification will override the DRCP fields, and further attempts to set the DRCP fields will then throw an error. Oracle recommends that the parameter be used instead of the DRCP fields.
To make it easier to modify the list, individual entries are indexed using the TYPE so it is not necessary to re-specify the entire list. For example, to adjust the number of DEDICATED brokers:
alter system set connection_brokers = '((TYPE=DEDICATED)(BROKERS=2))'
