Oracle教程 2023-02-24

Oracle 视图 V$AQ_SUBSCRIBER_LOAD 官方解释，作用，如何使用详细说明

本站中文解释

V$AQ_SUBSCRIBER_LOAD是Oracle AQ (异步队列)视图，它用来报告订户服务器的负载情况，其中每个订户服务器在收到消息之后被计量一次。该视图可以使用来分析系统的性能和负载。

通过使用 V$AQ_SUBSCRIBER_LOAD视图，可以查看订户服务器的负载情况，计算每个订户服务器的收件箱统计数据，以及逐个服务器的实时消息数量以及吞吐量。另外，它还可以查看服务器的状态(比如已激活和即将重新加载状态)，窗口消息缓存数量，以及某个订户服务器的消息重新加载次数。

使用V$AQ_SUBSCRIBER_LOAD视图的方法如下：SQL> select * from V$AQ_SUBSCRIBER_LOAD ;

官方英文解释

V$AQ_SUBSCRIBER_LOAD describes the load of all subscribers of sharded queues in terms of latency at every instance in an Oracle RAC environment.

Latency denotes the predicted amount of time (in seconds) required from the current time to drain all the messages for that subscriber at each respective instance. The latency calculation considers past enqueue/dequeue rates and future enqueue/dequeue rates based on history.

Note:

AQ sharded queues are deprecated in Oracle Database 21c. Oracle recommends that you instead use Transactional Event Queues (TEQs) for higher throughput and better performance.

Column	Datatype	Description
`QUEUE_ID`	`NUMBER`	Queue ID
`QUEUE_SCHEMA`	`VARCHAR2(128)`	Queue schema
`QUEUE_NAME`	`VARCHAR2(128)`	Queue name
`SUBSCRIBER_ID`	`NUMBER`	Subscriber ID
`SUBSCRIBER_NAME`	`VARCHAR2(128)`	Subscriber name
`LATENCY_STATE`	`VARCHAR2(8)`	Possible values: FINITE – The subscriber will be able to dequeue all the messages in a finite amount of time INFINITE – The subscriber’s dequeue rate may not catch up to the enqueue rate UNKNOWN – Latency is not yet known
`LATENCY`	`NUMBER`	Latency (in seconds). Valid only when `LATENCY_STATE` is `FINITE`.
`DEQUEUE_REQUESTS`	`NUMBER`	Approximate number of dequeue requests noted recently
`ACTIVE_SHARDS`	`NUMBER`	Number of queue shards that have messages for this subscriber
`ACTIVE_LISTENER`	`VARCHAR2(5)`	Indicates whether the subscriber is actively listening at this instance for messages (TRUE) or not (FALSE)
`DEQUEUE_SESSIONS`	`NUMBER`	Displays the number of active dequeue sessions for this subscriber
`FLAGS`	`NUMBER`	For internal use only
`MANDATORY_AFF_SWITCHES`	`NUMBER`	An affinity switch is a change in the dequeue instance for a shard-subscriber pair. A mandatory affinity switch is when there are local enqueues in the queue at the instance but no local dequeues present, so the dequeue affinity is switched to another instance for that shard-subscriber pair. This column shows the number of times mandatory affinity switches were needed from this instance to another for this subscriber.
`OPTIONAL_AFF_SWITCHES`	`NUMBER`	Optional affinity switches are affinity switches that are not mandatory. Optional affinity switches are done for global load balancing across the Oracle Real Application Clusters (Oracle RAC) database. This column shows the number of times optional affinity switches were needed from this instance to another for this subscriber.
`CON_ID`	`NUMBER`	The ID of the container to which the data pertains. Possible values include: `0`: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs. `1`: This value is used for rows containing data that pertain to only the root n: Where n is the applicable container ID for the rows containing data

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