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V$PGASTAT动态性能视图

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2022-03-06 / 0 评论 / 0 点赞 / 221 阅读 / 5,861 字 / 正在检测是否收录...
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介绍

V$PGASTAT视图会统计自实例启动以来的PGA内存使用情况以及PGA自动内存管理的统计信息,但注意,PGA自动内存管理统计的前提是PGA_AGGREGAET_TARGET参数必须有设置。

视图详情

字段名 字段类型 描述 备注
NAME VARCHAR2(64) Name of the statistic 统计的名称
VALUE NUMBER Statistic value 统计值
UNIT VARCHAR2(12) Unit for the value:
bytes
microseconds
percent
值单位:
字节
微秒
百分比

统计详情

说明:以下内容英文来自于Oracle官网,中文来自于翻译和个人理解。

aggregate PGA auto target

Amount of PGA memory the Oracle Database can use for work areas running in automatic mode. This amount is dynamically derived from the value of the PGA_AGGREGATE_TARGET initialization parameter and the current work area workload, and continuously adjusted by the Oracle Database.

Oracle数据库用于在自动内存模式下运行的工作区域的PGA内存量。这个数值是Oracle动态的从初始化参数PGA_AGGREGATE和当前工作区域的负载中得到的,并不断的进行调整。

If this value is small compared to the value of PGA_AGGREGATE_TARGET, then a large amount of PGA memory is used by other components of the system (for example, PL/SQL or Java memory) and little is left for work areas. The DBA must ensure that enough PGA memory is left for work areas running in automatic mode.

如果这个值小于PGA_AGGREGATE_TARGET的值,就说明系统的其他组件(例如PL/SQL或Java内存)会使用大量的PGA内存,那么留给工作区的内存就会很少。DBA必须要保证为自动内存模式下运行的工作区域留下足够的PGA内存。

aggregate PGA target parameter

Current value of the PGA_AGGREGATE_TARGET initialization parameter. If this parameter is not set, then its value is 0 and automatic management of PGA memory is disabled.

当前值是初始化参数PGA_AGGREGATE_TARGET的值,如果不设置该参数,则默认为0,就说明禁用PGA内存的自动管理功能。

bytes processed

Number of bytes processed by memory intensive SQL operators, cumulated since instance startup.

自实例启动以来,内存使用较大的SQL语句(内存密集型SQL)操作的字节数。

cache hit percentage

A metric computed by the Oracle Database to reflect the performance of the PGA memory component, cumulative since instance startup. A value of 100% means that all work areas executed by the system since instance startup have used an optimal amount of PGA memory.

是Oracle计算出来的指标,反映了自实例启动以来累积的PGA内存组件的性能。当值为100%时,意味着自实例启动以来系统执行的所有工作区域都使用了最优的PGA内存。

When a work area cannot run optimal, one or more extra passes is performed over the input data. This will reduce the cache hit percentage in proportion to the size of the input data and the number of extra passes performed.

当工作区域不能最佳运行时,会对输入的数据执行一次或多次额外的传递。会根据输入数据的大小和执行的额外传递次数,按比例降低缓存命中率。

extra bytes read/written

Number of bytes processed during extra passes of the input data, cumulated since instance startup. When a work area cannot run optimal, one or more of these extra passes is performed.

自实例启动以来,执行额外传递输入数据期间处理的字节数。当工作区域不能最佳运行时,会对输入的数据执行一次或多次额外的传递。

global memory bound

Maximum size of a work area executed in automatic mode. This value is continuously adjusted by the Oracle Database to reflect the current state of the work area workload. The global memory bound generally decreases when the number of active work areas is increasing in the system.

在自动PGA内存管理模式下执行的工作区域的最大大小。该值由Oracle数据不断调整,以反应工作区域负载的状态。当系统中活动工作区的数量增加时,全局内存边界通常会减少。

If the value of the global bound decreases below 1 MB, then the value of PGA_AGGREGATE_TARGET should be increased.

如果全局绑定的值减少到了1MB以下,就应该增加PGA_AGGREGATE_TARGET的值。

max processes count

Maximum number of processes active at any one time since instance startup.

自实例启动以来,每次活动的最大进程数量。

maximum PGA allocated

Maximum number of bytes of PGA memory allocated at one time since instance startup.

自实例启动以来,PGA内存分配的最大字节数。

maximum PGA used for auto workareas

Maximum amount of PGA memory consumed at one time by work areas running under the automatic memory management mode since instance startup.

自实例启动以来,自动内存管理模式下运行的工作区一次消耗的最大PGA内存的数量。

maximum PGA used for manual workareas

Maximum amount of PGA memory consumed at one time by work areas running under the manual memory management mode since instance startup.

自实例启动以来,手动内存管理模式下运行的工作区一次消耗的最大PGA内存的数量。

over allocation count

This statistic is cumulative since instance startup. Over allocating PGA memory can happen if the value of PGA_AGGREGATE_TARGET is too small. When this happens, the Oracle Database cannot honor the value of PGA_AGGREGATE_TARGET and extra PGA memory needs to be allocated.

这个统计值是自实例启动以来累积的。如果PGA_AGGREGATE_TARGET的值过小,就会发生过度分配PGA内存的情况。当出现这种情况时,Oracle数据库就不遵循PGA_AGGREGATE_TARGET的值,需要分配额外的PGA内存。

If over allocation occurs, then increase the value of PGA_AGGREGATE_TARGET using the information provided by the V$PGA_TARGET_ADVICE view.

如果出现超额分配的问题,则使用V$PGA_TARGET_ADVICE视图提供的信息增加PGA_AGGREGATE_TARGET的值。

PGA memory freed back to OS

Number of bytes of PGA memory freed back to the operating system, cumulated since instance startup.

自实例启动以来,释放回操作系统的PGA内存字节数。

process count

Number of processes active within up to the last 3 seconds.

最近三秒内活动的进程数。

recompute count (total)

Number of times the instance bound, which is a cap on the maximum size of each active work area, has been recomputed since instance startup. Generally, the instance bound is recomputed in the background every 3 seconds, but it could be recomputed by a foreground process when the number of work areas changes rapidly in a short period of time.

实例启动以来重新计算实例绑定的次数,即每个活动工作区的最大上限大小。通常情况下,实例的边界每3秒会在后台重新计算一次,但当工作区的数量在短时间内迅速变化时,它可以由前台进程进行计算。

total freeable PGA memory

Number of bytes of PGA memory in all processes that could be freed back to the operating system.

所有进程中可以释放回操作系统的PGA内存字节数。

total PGA allocated

Current amount of PGA memory allocated by the instance. The Oracle Database attempts to keep this number below the value of the PGA_AGGREGATE_TARGET initialization parameter. However, it is possible for the PGA allocated to exceed that value by a small percentage and for a short period of time when the work area workload is increasing very rapidly or when PGA_AGGREGATE_TARGET is set to a small value.

实例分配的当前PGA内存的数量。Oracle会视图去保持这个数值低于PGA_AGGREGATE_TARGET初始化参数的值,但是,当工作区的工作负载快速增加或将PGA_AGGREGATE_TARGET设置为一个较小的值时,分配的PGA就可能会超过该值。

total PGA inuse

Indicates how much PGA memory is currently consumed by work areas. This number can be used to determine how much memory is consumed by other consumers of the PGA memory (for example, PL/SQL or Java).

工作区当前已消耗的PGA内存量。这个数值可以用来确定PGA内存的其他使用者(例如PL/SQL或Java)消耗了多少内存。

total PGA used for auto workareas

Indicates how much PGA memory is currently consumed by work areas running under the automatic memory management mode. This number can be used to determine how much memory is consumed by other consumers of the PGA memory (for example, PL/SQL or Java).

当前在自动PGA内存管理模式下运行的工作区域所消耗的内存数量。这个数值可以用来确定PGA内存的其他使用者(例如PL/SQL或Java)使用了多少内存。

total PGA used for manual workareas

Indicates how much PGA memory is currently consumed by work areas running under the manual memory management mode. This number can be used to determine how much memory is consumed by other consumers of the PGA memory (for example, PL/SQL or Java).

当前在手动PGA内存管理模式下运行的工作区域所消耗的内存数量。这个数值可以用来确定PGA内存的其他使用者(例如PL/SQL或Java)使用了多少内存。

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