当db_cache_advice初始化参数设为on, 大大降低了cpu的使用

7.2.2.1 Buffer Cache Advisory Statistics

A number of statistics can be used to examine buffer cache activity. These include the following:

V$DB_CACHE_ADVICE

Buffer cache hit ratio

buffer cache 报告的统计

统计的数据能被用于检查buffer cache的活动。
7.2.2.2 Using V$DB_CACHE_ADVICE

This view is populated when the DB_CACHE_ADVICE initialization parameter is set toON. This view shows the simulated miss rates for a range of potential buffer cache sizes.

当db_cache_advice初始化参数设为on，这个视图会一直增加。这个视图显示了一整套的关于buffer cache大小的模拟的缺失率。

Each cache size simulated has its own row in this view, with the predicted physical I/O activity that would take place for that size. TheDB_CACHE_ADVICE parameter is dynamic, so the advisory can be enabled and disabled dynamically to allow you to collect advisory data for a specific workload.

在视图中每个缓存的模拟大小有他自己的一行数据。设置不同的大小，预测物理i/o的活动。db_cache_advice参数是动态的。所以报告能被开启和关闭允许你收集一个具体的工作量的报告数据。

There is some overhead associated with this advisory. When the advisory is enabled, there is a small increase in CPU usage, because additional bookkeeping is required.

有一些与这个报告相关联的开销,当这个报告被开启,将有少量增加cpu的使用.因为增加额外的记录是必须的.

Oracle uses DBA-based sampling to gather cache advisory statistics. Sampling substantially reduces both CPU and memory overhead associated with bookkeeping. Sampling is not used for a buffer pool if the number of buffers in that buffer pool is small to begin with.

oracle使用dba为基础取样收集缓存的统计报告,取样大大降低了cpu的使用和内存开销和额外的记录.

To use V$DB_CACHE_ADVICE, the parameter DB_CACHE_ADVICE should be set toON, and a representative workload should be running on the instance. Allow the workload to stabilize before querying theV$DB_CACHE_ADVICE view.

想要使用v$db_cache_advice视图.db_cache_advice参数一定要设置成on状态.和一个典型的工作量应该被运行在实例上.在查询v$db_cache_advice视图之前使工作量稳定.

The following SQL statement returns the predicted I/O requirement for the default buffer pool for various cache sizes:

如下的sql语句各种不同的缓存大小跟不同的I/o关连.

SELECT size_for_estimate, buffers_for_estimate, estd_physical_read_factor, estd_physical_reads FROM V$DB_CACHE_ADVICE WHERE name = 'DEFAULT' AND block_size = (SELECT value FROM V$PARAMETER WHERE name = 'db_block_size') AND advice_status = 'ON';

The following output shows that if the cache was 212 MB, rather than the current size of 304 MB, the estimated number of physical reads would increase by a factor of 1.74 or 74%. This means it would not be advisable to decrease the cache size to 212MB.

下面输出显示如果缓存是212M,而不是当前的304M,估计物理读的数量将增加1.74,这就意味着降低到212M是不可取的,oracle视频教程下载.

当db_cache_advice初始化参数设为on, 大大降低了cpu的使用相关推荐

sap oracle 内存参数,ORACLE 25个需要深思熟虑重要的初始化参数
此内容摘自 ORACLE 11gR2性能调整与优化一书,做为一个自己的笔记 1 MEMORY_TARGET : 这个初始化参数设定分配给PGA和SGA 的所有内存(11g 新参数).设置了MEMORY ...
oracle启用amm,Oracle11g自动内存管理(AMM)相关的初始化参数
ORACLE对内存的管理越来越趋向智能化.自动化,从9i通过PGA_AGGREGATE_TARGET参数实现PGA的自动管理,10g通过Automatic Shared Memory Manageme ...
oracle内存管理模式amm,Oracle 11g自动内存管理(AMM)相关的初始化参数
Oracle对内存的管理越来越趋向智能化.自动化,从9i通过PGA_AGGREGATE_TARGET参数实现PGA的自动管理,10g通过Automatic Shared Memory Manageme ...
Servlet的初始化参数
确保接收和输出的数据不出现乱码.需要对request和response进行转码 request.setCharacterEncoding(charset);response.setCharacterE ...
ORACLE初始化参数文件概述
ORACLE初始化参数文件概述在9i之前,参数文件只有一种,它是文本格式的,称为pfile,在9i及以后的版本中,新增了服务器参数文件,称为spfile,它是二进制格式的.这两种参数文件都是用来存储 ...
SpringMvc CharacterEncodingFilter 解析 encoding 参数并初始化参数
SpringMvc CharacterEncodingFilter 解析 encoding 参数并初始化参数: 转载于:https://www.cnblogs.com/xiluhua/p/974632 ...
springmvc的初始化参数绑定
一.springmvc的初始化参数绑定此种和我们之前说的类型转换非常相似,可以看作是一种类型转换在初始化参数绑定时重要的是参数类型 -------------------单日期的绑定二. 配 ...
Android MIPI转LVDS显示屏调试之---SN65DSI84初始化参数的确定(3)
基于高通Msm8937平台,SN65DSI84后面简称DSI84. 打开DSI Tuner,选择目标设备,这里我们是SN65DSI84 Panel Inputs 1.1 Panel Info 这些数 ...
java数据库初始化参数,oracle数据库初始化参数设置--Java免费学习网
正在看的ORACLE教程是:oracle初始化参数设置.ALTER DATABASE DATAFILE'd:ORANTDATABASEUSER1ORCL.ORA' RESIZE 1000M; CREA ...

当db_cache_advice初始化参数设为on, 大大降低了cpu的使用

当db_cache_advice初始化参数设为on, 大大降低了cpu的使用相关推荐

最新文章

热门文章