Oracle 视图 V$SQL_WORKAREA_HISTOGRAM 官方解释，作用，如何使用详细说明
本站中文解释
该视图表示每个工作区所用内存量的直方图，可以在调查结果中使用它：
1、提供对资源使用情况的诊断：可以将工作区分为不同的组，并分析每个组中的内存使用情况，以及比较作业之间的差异；
2、提供对系统性能的重构建议：例如，可以根据V$SQL_WORKAREA_HISTOGRAM提示有可能改变，以克服内存使用过多耗尽资源的问题；
3、用于更好地审查系统的其他问题：例如，可以确定工作区深度是否导致并行应用程序运行效率低下；
4、提供对工作区执行 预测：与V$SQL_WORKAREA_ACTIVE视图配合，可以快速调试系统需要多少内存来运行作业。
官方英文解释
V$SQL_WORKAREA_HISTOGRAM displays the cumulative work area execution statistics (cumulated since instance startup) for different work area groups. The work areas are split into 33 groups based on their optimal memory requirements with the requirements increasing in powers of two. That is, work areas whose optimal requirement varies from 0 KB to 1 KB, 1 KB to 2 KB, 2 KB to 4 KB, … and 2 TB to 4 TB.
For each work area group, the V$SQL_WORKAREA_HISTOGRAM view shows how many work areas in that group were able to run in optimal mode, how many were able to run in one-pass mode, and finally how many ran in multi-pass mode. The DBA can take a snapshot at the beginning and the end of a desired time interval to derive the same statistics for that interval.
| Column | Datatype | Description |
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Lower bound for the optimal memory requirement of work areas included in this row (bytes) |
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Upper bound for the optimal memory requirement of work areas included in this row (bytes) |
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Number of work areas with an optimal memory requirement comprised between |
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Number of work areas with an optimal memory requirement comprised between |
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Number of work areas with an optimal memory requirement comprised between |
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Sum of |
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The ID of the container to which the data pertains. Possible values include:
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See Also:
Oracle Database
Performance Tuning Guide for detailed information on how to monitor automatic PGA memory performance using this view
