Oracle教程 2023-02-24

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

本站中文解释

Oracle视图V$AQ_MESSAGE_CACHE显示应用程序正在缓存AQ消息的状态。这个视图有助于检测AQ消费者是否正确及及时地缓存消息。

要使用这个视图，可以使用SELECT语句来检索缓存的消息信息：

SELECT * FROM v$aq_message_cache;

要更详细地了解缓存中的消息，可以使用WHERE子句：

SELECT * FROM v$aq_message_cache
WHERE consumer_name = ‘name_of_consumer’;

where name_of_consumer是要查询的消费者名称。

官方英文解释

V$AQ_MESSAGE_CACHE provides performance statistics of the message cache for sharded queues at the subshard level in the instance.

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
`SHARD_ID`	`NUMBER`	Shard ID
`PRIORITY`	`NUMBER`	Priority of the subshard for dequeue, range `0-9`
`SUBSHARD_ID`	`NUMBER`	Subshard ID in the shard
`PARTITION_ID`	`NUMBER`	Partition id for the particular subshard
`MAX_MSGS`	`NUMBER`	Maximum number of messages of subshard
`ENQUEUED_MSGS`	`NUMBER`	Number of messages enqueued for the subshard
`MSGS_MADE_EXPIRED`	`NUMBER`	Number of messages made expired
`CHUNK_SIZE`	`NUMBER`	The size of the memory chunk for storing messages
`NUM_CHUNKS`	`NUMBER`	Number of chunks for the subshard
`NUM_FREE_CHUNKS`	`NUMBER`	Number of free chunks for the subshard
`USED_MEMORY_SIZE`	`NUMBER`	Total estimated size of memory in use (in bytes) for the subshard
`STATE`	`VARCHAR2(13)`	Subshard state. Possible values: `CACHED` (in memory) `UNCACHED` (on disk) `UNCACHED_FREE` `CACHED_FREE` `UNKNOWN`
`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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官方英文解释

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