Oracle教程 2023-02-24

Oracle 视图 DBA_HIST_SQL_WORKAREA_HSTGRM 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_SQL_WORKAREA_HSTGRM是从8i开始就有的与SQL缓冲区池相关的视图，用于显示SQL缓冲池和SQL操作相关信息。它可以用来监控SQL缓冲区池的变化同时记录SQL工作区和SQL缓冲区池使用情况。

它提供了以下主要功能：

1. 查询SQL缓冲区池的缓存大小，了解不同的SQL所使用的缓存大小；
2. 使用者可以根据当前的SQL使用情况，来分析是否需要调整SQL缓冲池的大小；
3. 查询活跃的SQL缓冲区池的变化情况，以及缓存的效率和命中概率等；
4. 监控SQL响应时间，了解SQL执行情况，以便及时调整。

使用方法：

可以利用SQL命令来查询DBA_HIST_SQL_WORKAREA_HSTGRM视图，从而获取SQL缓冲区池的缓存大小，SQL操作的信息，以及SQL缓冲区池的使用情况等。

具体的SQL语句如下：

SELECT * FROMDBA_HIST_SQL_WORKAREA_HSTGRM;

官方英文解释

DBA_HIST_SQL_WORKAREA_HSTGRM displays the historical cumulative work area execution statistics (cumulated since instance startup) for different work area groups.

This view contains snapshots of V$SQL_WORKAREA_HISTOGRAM.

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
`LOW_OPTIMAL_SIZE`	`NUMBER`	`NOT NULL`	Lower bound for the optimal memory requirement of work areas included in the row (in bytes)
`HIGH_OPTIMAL_SIZE`	`NUMBER`	`NOT NULL`	Upper bound for the optimal memory requirement of work areas included in the row (in bytes)
`OPTIMAL_EXECUTIONS`	`NUMBER`		Number of work areas with an optimal memory requirement comprised between `LOW_OPTIMAL_SIZE` and `HIGH_OPTIMAL_SIZE` which have been executed in optimal mode since instance startup
`ONEPASS_EXECUTIONS`	`NUMBER`		Number of work areas with an optimal memory requirement comprised between `LOW_OPTIMAL_SIZE` and `HIGH_OPTIMAL_SIZE` which have been executed in one-pass mode since instance startup
`MULTIPASSES_EXECUTIONS`	`NUMBER`		Number of work areas with an optimal memory requirement comprised between `LOW_OPTIMAL_SIZE` and `HIGH_OPTIMAL_SIZE` which have been executed in multi-pass mode since instance startup
`TOTAL_EXECUTIONS`	`NUMBER`		Sum of `OPTIMAL_EXECUTIONS`, `ONEPASS_EXECUTIONS`, and `MULTIPASSES_EXECUTIONS`
`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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