Oracle教程 2023-02-25

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

本站中文解释

Oracle视图V$ACTIVITY_MVIEW提供了一些有关当前会话中表空间或竞争变更的活动信息。该视图报告所有未完成的索引，表和快照切换。可以通过查询该视图来检索信息，以便监视和估计未完成的DML操作和快照切换的时间长度和完成的可能性。

V$ACTIVITY_MVIEW的主要用途就是可以帮助用户监控表空间。可以查看未完成的操作和其它数据库活动。

要使用V$ACTIVITY_MVIEW，请通过使用SELECT命令来查询和跟踪一个或多个会话的活动状况，可以按如下方式来查询：
select * from v$activity_mview
where session_id=&session_id

官方英文解释

V$ACTIVITY_MVIEW describes the materialized view activity snapshots that are currently being taken by the Object Activity Tracking System (OATS).

Each row in this view represents one in-progress activity snapshot and describes the materialized view activity that has occurred so far during the snapshot interval.

Column	Datatype	Description
`MVIEW_NAME`	`VARCHAR2(128)`	Name of the materialized view for which the activity snapshot is being taken
`MVIEW_OWNER`	`VARCHAR2(128)`	Owner of the materialized view for which the activity snapshot is being taken
`USER_CLASS`	`VARCHAR2(7)`	Indicates whether the activity was performed by the RDBMS (`SYS`) or by a user (`NON-SYS`)
`COMPILES`	`NUMBER`	Number of times the materialized view was compiled This number includes: Explicit compiles performed with the SQL statement `ALTER` `MATERIALIZED` `VIEW` … `COMPILE` Automatic compiles that occurred because the structure of an underlying base table changed
`REWRITES_TEXTMATCH`	`NUMBER`	Number of query rewrites that used the text match rewrite method
`REWRITES_GENERAL`	`NUMBER`	Number of query rewrites that used general rewrite methods
`REWRITES_PARTIAL`	`NUMBER`	Number of query rewrites that occurred when the view was partially stale This number includes: `UNION` `ALL` operations involving rewritten queries that had one branch with the materialized view and the other branch with its underlying base tables (partial rewrites) Single query block rewrites of the materialized view that involved a join back to its underlying base table
`REWRITES_DELTA`	`NUMBER`	Number of query rewrites that used stale data in the materialized view plus the delta information stored in the materialized view logs
`REWRITES_PCT`	`NUMBER`	Number of partition change tracking (PCT) rewrites
`REWRITES_HINTED`	`NUMBER`	Number of query rewrites that occurred because the materialized view was eligible for query rewrite and the `SELECT` statement contained the `REWRITE` hint with the name of the materialized view specified in the hint
`NOREWRITES_HINTED`	`NUMBER`	Reserved for future use
`NOREWRITES_STALE`	`NUMBER`	Number of query executions that did not use query rewrite because the materialized view was eligible for query rewrite, but stale
`REFRESHES_ON_DEMAND`	`NUMBER`	Number of `ON` `DEMAND` refreshes This type of refresh is performed on materialized views that use the `ON` `DEMAND` refresh mode, which instructs the database to refresh the materialized view only when a manual refresh is launched by one of the three `DBMS_MVIEW` refresh procedures.
`REFRESHES_ON_COMMIT`	`NUMBER`	Number of `ON` `COMMIT` refreshes This type of refresh is performed on materialized views that use the `ON` `COMMIT` refresh mode, which instructs the database to refresh the materialized view whenever the database commits a transaction that operates on a master table of the materialized view.
`REFRESHES_ON_STATEMENT`	`NUMBER`	Number of `ON` `STATEMENT` refreshes This type of refresh is performed on materialized views that use the `ON` `STATEMENT` refresh mode, which instructs the database to perform an automatic refresh of the materialized view every time a DML operation is performed on any of the view’s base tables.
`REFRESHES_SCHEDULED`	`NUMBER`	Number of scheduled refreshes
`REFRESHES_AUTOMATIC`	`NUMBER`	Number of automatic refreshes
`REFRESHES_FAST`	`NUMBER`	Number of incremental refreshes
`REFRESHES_COMPLETE`	`NUMBER`	Number of full refreshes
`REFRESHES_PCT`	`NUMBER`	Number of partition change tracking (PCT) refreshes
`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

Note:

The counts in this view are approximate in order to keep system overhead low. Also, there are database activities, such as statistics collection, query compilation, and query optimization, that may cause the counts to be different than expected or to vary slightly across successive queries.

Note:

This view is available starting with Oracle Database 21c.

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