Oracle教程 2023-04-07

Oracle 视图 DBA_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DBA_ACTIVITY_MVIEW提供了Database Performance Analyzer (DPA) 对全局数据库性能的诊断信息的快照。它显示数据库处理总量、活动会话、生存期和性能指标。

DPA_ACTIVITY_MVIEW视图提供了一组和其他视图用于诊断特定的性能数据。这包括下面的列：DPA_ACTIVITY_MVIEW.ID，DPA_ACTIVITY_MVIEW.SESSION_ID，DPA_ACTIVITY_MVIEW.SESSION_DB_ID，DPA_ACTIVITY_MVIEW.SESSION_USER，DPA_ACTIVITY_MVIEW.SESSION_SERVICE_NAME，DPA_ACTIVITY_MVIEW.LAST_ACTIVE_TIME，DPA_ACTIVITY_MVIEW.TOTAL_WORK，DPA_ACTIVITY_MVIEW.SEQUENCE_NUMBER，DPA_ACTIVITY_MVIEW.LOAD_TIME例如，要检索最活跃的会话，您可以使用以下查询：

SELECT *
FROM DPA_ACTIVITY_MVIEW
ORDER BY LAST_ACTIVE_TIME DESC;

此外，DBA_ACTIVITY_MVIEW视图还可以用来根据请求的特定指标，如服务器活动会话数，使用统计函数等来跟踪特定的性能指标及时间。

官方英文解释

DBA_ACTIVITY_MVIEW describes materialized view activity snapshots that were recently taken by the Object Activity Tracking System (OATS).

Each row in this view represents one recently completed activity snapshot and describes the materialized view activity that occurred during the snapshot interval.

Column	Datatype	NULL	Description
`SNAP_ID`	`NUMBER`	`NOT NULL`	Activity snapshot identifier
`CON_DBNAME`	`VARCHAR2(128)`	`NOT NULL`	Name of the container to which the data pertains
`INSTANCE_NUMBER`	`NUMBER`	`NOT NULL`	Identifier for the instance in which the activity snapshot was taken
`BEGIN_TIME`	`TIMESTAMP(3)`	`NOT NULL`	Begin time for the activity snapshot interval
`END_TIME`	`TIMESTAMP(3)`	`NOT NULL`	End time for the activity snapshot interval
`MVIEW_NAME`	`VARCHAR2(128)`	`NOT NULL`	Name of the materialized view for which the activity snapshot was taken
`MVIEW_OWNER`	`VARCHAR2(128)`	`NOT NULL`	Owner of materialized view for which the activity snapshot was 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

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.

本站中文解释

官方英文解释

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