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.

Indicates whether the activity was performed by the RDBMS (SYS) or by a user (NON-SYS)

Explicit compiles performed with the SQL statement ALTER MATERIALIZED VIEW … COMPILE

Automatic compiles that occurred because the structure of an underlying base table changed

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

Number of query rewrites that used stale data in the materialized view plus the delta information stored in the materialized view logs

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

Number of query executions that did not use query rewrite because the materialized view was eligible for query rewrite, but stale

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.

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.

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.

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.

See Also:

V$ACTIVITY_MVIEW to view in-progress materialized view activity snapshots

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数据库远程运维 Oracle 视图 DBA_ACTIVITY_MVIEW 官方解释，作用，如何使用详细说明