Oracle教程 2023-02-25

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

本站中文解释

V$STREAMS_APPLY_COORDINATOR是Oracle中的一个视图，它可以帮助DBA了解流应用程序的当前调度、控制和传输的状态、参数和统计信息。它可以用来帮助DBA查看当前应用程序的工作负载，排查问题，并测试实时流式处理应用程序的性能。

使用V$STREAMS_APPLY_COORDINATOR视图需要具有SYSDBA角色的权限。要理解上面的信息，视图中的表列及其含义，可以执行以下查询：

SELECT * FROM v$streams_apply_coordinator;

上面的查询可以输出表的各个列，其中有一些会显示当前流应用程序的传输状态、工作负载、性能统计等。下面是其中一些常见的列：

APPLY_NAME：应用程序的名称
DOP：并行度，指定应用程序将使用几个并发会话去解决查询
SCHEDULE：定义是否禁用调度器或仅使用它运行查询
CONSUMER_GROUP：该值对应了流使用的消费者组
MESSAGES_ENQUEUED：消息积压量
MESSAGES_DEQUEUED：已处理消息的数量
ENQUEUE_STALLED：未能在指定的时间内完成入队的消息的数量
DEQUEUE_ERRORS：尝试从队列中读取消息失败的数量
RULE_EVALUATOR_IDLE：用于识别规则的空闲会话的数量
APPLY_IDLE：适应器空闲会话的用量

官方英文解释

V$STREAMS_APPLY_COORDINATOR displays information about each apply process coordinator. The coordinator for an apply process gets transactions from the apply process reader and passes them to apply servers. An apply process coordinator is a subcomponent of an apply process, outbound server, or inbound server.

Column	Datatype	Description
`SID`	`NUMBER`	Session ID of the coordinator’s session
`SERIAL#`	`NUMBER`	Serial number of the coordinator’s session
`STATE`	`VARCHAR2(21)`	State of the coordinator: `INITIALIZING` – Starting up `IDLE` – Performing no work `APPLYING` – Passing transactions to apply servers `SHUTTING DOWN CLEANLY` – Stopping without an error `ABORTING` – Stopping because of an apply error
`APPLY#`	`NUMBER`	Apply process number. An apply process coordinator is an Oracle background process, prefixed by `ap`.
`APPLY_NAME`	`VARCHAR2(128)`	Name of the apply process
`TOTAL_APPLIED`	`NUMBER`	Total number of transactions applied by the apply process since the apply process was last started
`TOTAL_WAIT_DEPS`	`NUMBER`	Number of times since the apply process was last started that an apply server waited to apply a logical change record (LCR) in a transaction until another apply server applied a transaction because of a dependency between the transactions
`TOTAL_WAIT_COMMITS`	`NUMBER`	Number of times since the apply process was last started that an apply server waited to commit a transaction until another apply server committed a transaction to serialize commits
`TOTAL_ADMIN`	`NUMBER`	Number of administrative jobs issued since the apply process was last started
`TOTAL_ASSIGNED`	`NUMBER`	Number of transactions assigned to apply servers since the apply process was last started
`TOTAL_RECEIVED`	`NUMBER`	Total number of transactions received by the coordinator process since the apply process was last started
`TOTAL_IGNORED`	`NUMBER`	Number of transactions which were received by the coordinator but were ignored because they had been previously applied
`TOTAL_ROLLBACKS`	`NUMBER`	Number of transactions which were rolled back due to unexpected contention
`TOTAL_ERRORS`	`NUMBER`	Number of transactions applied by the apply process that resulted in an apply error since the apply process was last started
`UNASSIGNED_COMPLETE_TXNS`	`NUMBER`	Total number of complete transactions that the coordinator has not assigned to any apply servers
`AUTO_TXN_BUFFER_SIZE`	`NUMBER`	Current value of transaction buffer size. Transaction buffer size refers to the number of transactions that the apply reader can assemble ahead of apply servers. The apply process periodically adjusts the transaction buffer size.
`LWM_TIME`	`DATE`	Time when the message with the lowest message number was recorded. The creation time of the message with the lowest message number was also recorded at this time.
`LWM_MESSAGE_NUMBER`	`NUMBER`	Number of the message corresponding to the low watermark. That is, messages with a commit message number less than or equal to this message number have definitely been applied, but some messages with a higher commit message number also may have been applied.
`LWM_MESSAGE_CREATE_TIME`	`DATE`	For captured messages, creation time at the source database of the message corresponding to the low watermark. For user-enqueued messages, time when the message corresponding to the low watermark was enqueued into the queue at the local database.
`HWM_TIME`	`DATE`	Time when the message with the highest message number was recorded. The creation time of the message with the highest message number was also recorded at this time.
`HWM_MESSAGE_NUMBER`	`NUMBER`	Number of the message corresponding to the high watermark. That is, no messages with a commit message number greater than this message number have been applied.
`HWM_MESSAGE_CREATE_TIME`	`DATE`	For captured messages, creation time at the source database of the message corresponding to the high watermark. For user-enqueued messages, time when the message corresponding to the high watermark was enqueued into the queue at the local database.
`STARTUP_TIME`	`DATE`	Time when the apply process was last started
`ELAPSED_SCHEDULE_TIME`	`NUMBER`	Time elapsed (in hundredths of a second) scheduling messages since the apply process was last started
`ELAPSED_IDLE_TIME`	`NUMBER`	Elapsed idle time
`LWM_POSITION`	`RAW(64)`	Position of the low-watermark LCR
`HWM_POSITION`	`RAW(64)`	Position of the high-watermark LCR
`PROCESSED_MESSAGE_NUMBER`	`NUMBER`	Message number currently processed by the apply coordinator
`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
`ACTIVE_SERVER_COUNT`	`NUMBER`	Active server count

Note:

The ELAPSED_SCHEDULE_TIME column is only populated if the TIMED_STATISTICS initialization parameter is set to true, or if the STATISTICS_LEVEL initialization parameter is set to TYPICAL or ALL.

本站中文解释

官方英文解释

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