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

Oracle视图DBA_HIST_SESS_SGA_STATS用于描述会话类的SGA和共享内存区结构的历史状态。它报告每个会话访问共享内存区大小，以及每秒或每次查询期间实际会话访问数量。

该视图可以用于评估该平台上会话处理影响SGA的使用程度，并确定会话实体中最占用资源的会话。可以帮助确定是否需要更改SGA大小以及会话活动是否受到STS或SMS控制对象的影响。

使用方法：

SELECT
，sample_time
FROM
dba_hist_sess_sga_stats
GROUP BY
sample_time

ORDER BY
sample_time;

上述查询用于按时间顺序提取DBA_HIST_SESS_SGA_STATS中的采样时间。下一步是根据所选采样时间检索所需的活动。

DBA_HIST_SESS_SGA_STATS shows usage statistics for high utilization Oracle GoldenGate and XStream sessions.

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`	Instance number for the snapshot
`OBJECT_NAME`	`VARCHAR2(128)`	`NOT NULL`	Object name
`SESSION_TYPE`	`VARCHAR2(64)`	`NOT NULL`	Type of session
`SESSION_MODULE`	`VARCHAR2(64)`	`NOT NULL`	Session module. Valid values: XStream GoldenGate
`SGA_USED`	`NUMBER`		The total amount of shared memory (in bytes) currently used by the session out of the amount allocated (`SGA_ALLOCATED`)
`SGA_ALLOCATED`	`NUMBER`		The total amount of shared memory (in bytes) allocated from the pool for the session
`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