Oracle教程 2023-04-08

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

_STATS

Oracle视图DBA_HIST_OPTIMIZER_ENV_STATS存储着每个优化器环境统计的历史信息，包括特定类型的SQL语句在某个时间段内的优化器环境设定，以及优化器环境参数的推荐值。

使用此视图，开发者可以查看特定时间段内优化器环境参数的性能，并分析可能改善性能的优化器环境设置，以及特定类型SQL语句的优化器环境设定。开发者可以使用此视图来监控和改变优化器环境，进而实现性能优化。

DBA_HIST_OPTIMIZER_ENV displays the optimizer environments that have been captured in the Workload Repository.

This view is used with the DBA_HIST_SQLSTAT view.

Column	Datatype	NULL	Description
`DBID`	`NUMBER`	`NOT NULL`	Database ID
`OPTIMIZER_ENV_HASH_VALUE`	`NUMBER`	`NOT NULL`	Hash value for the optimizer environment
`OPTIMIZER_ENV`	`RAW(2000)`		Optimizer environment
`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