Oracle教程 2023-02-24

Oracle 视图 DBA_HIST_PGASTAT 官方解释，作用，如何使用详细说明

本站中文解释

Oracle视图DBA_HIST_PGASTAT是一个系统数据字典视图，包含有关PGA（即专用性能区）的历史信息。它显示了PGA内存的物理分配和使用情况，以及有关PGA的活动，这些活动包括应用程序向PGA中分配内存的作业，以及在PGA中处理的活动。此信息可用于检查PGA的性能，为诊断性能问题提供参考。

使用此视图，可以确定当前PGA的大小和内存分配，以及连接期间PGA是如何发展的。可以利用这些信息，调整PGA空间，以满足目标性能要求。要查询此视图，可以运行如下SQL查询：

SELECT SNAP_ID, INSTANCE_NUMBER，PGA_ALLOCATED, PGA_USED
FROM DBA_HIST_PGASTAT
WHERE SNAP_ID = (SELECT MAX (SNAP_ID) FROM DBA_HIST_SNAPSHOT);

这段SQL将向您提供SNAP_ID，INSTANCE_NUMBER，PGA_ALLOCATED和PGA_USED列的当前值。

官方英文解释

DBA_HIST_PGASTAT displays historical PGA memory usage statistics as well as statistics about the automatic PGA memory manager when it is enabled.

This view contains snapshots of V$PGASTAT.

Column	Datatype	NULL	Description
`SNAP_ID`	`NUMBER`	`NOT NULL`	Unique snapshot ID
`DBID`	`NUMBER`	`NOT NULL`	Database ID for the snapshot
`INSTANCE_NUMBER`	`NUMBER`	`NOT NULL`	Database instance number
`NAME`	`VARCHAR2(64)`	`NOT NULL`	Name of the statistic: `aggregate PGA auto target` `aggregate PGA target parameter` `bytes processed` `cache hit percentage` `extra bytes read/written` `global memory bound` `max processes count` `maximum PGA allocated` `maximum PGA used for auto workareas` `maximum PGA used for manual workareas` `over allocation count` `PGA memory freed back to OS` `process count` `recompute count (total)` `total freeable PGA memory` `total PGA allocated` `total PGA inuse` `total PGA used for auto workareas` `total PGA used for manual workareas` See Also: `V$PGASTAT` for descriptions of the statistics
`VALUE`	`NUMBER`		Statistic value
`CON_DBID`	`NUMBER`		The database ID of the PDB for the sampled session
`CON_ID`	`NUMBER`		The ID of the container that `CON_DBID` identifies. 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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