Oracle教程 2023-04-04

Oracle 视图 V$SGASTAT 官方解释，作用，如何使用详细说明

V$SGASTAT视图用于显示SGA中每个组件的内存使用情况。它包含指定组件中每个元素的总量、已分配的量及可用的量等信息。可以用于自动监控，以及指导在增加、减少或者调整内存时对SGA大小进行优化。

使用V$SGASTAT视图的步骤如下：

1. 首先使用v$sgastat视图查询所有的内存组件
例如：
SELECT name, pool, bytes/1024/1024 MBFREE FROM v$sgastat;

2. 根据SGA中的memory components分析其当前的内存使用情况

3. 根据使用情况，调整SGA的1M大小及内存组件的设置，以便于更有效地使用SGA内存

注意：在使用该视图前，应先执行alter system flush shared_pool命令，以保证SGA中的各组件使用情况的准确性和一致性。

V$SGASTAT displays detailed information on the system global area (SGA).

Column	Datatype	Description
`POOL`	`VARCHAR2(14)`	Designates the pool in which the memory in `NAME` resides: `in-memory pool` – Memory is allocated from the In-Memory pool `java pool` – Memory is allocated from the Java pool `large pool` – Memory is allocated from the large pool `numa pool` – Memory is allocated from the NUMA pool `shared pool` – Memory is allocated from the shared pool `streams pool` – Memory is allocated from the Streams pool
`NAME`	`VARCHAR2(26)`	SGA component name
`BYTES`	`NUMBER`	Memory size (in bytes)
`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

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