V$LATCH_CHILDREN视图

发布时间:2020-06-15 08:50:45 作者:onlinekof2001
来源:网络 阅读:523

http://docs.oracle.com/database/121/REFRN/refrn30109.htm

V$LATCH_CHILDREN

V$LATCH_CHILDREN displays statistics about child latches. This view includes all columns of V$LATCH plus the CHILD# column. Note that child latches have the same parent if their LATCH# columns match each other.

ColumnDatatypeDescription
ADDRRAW(4 | 8)Address of the latch object
LATCH#NUMBERLatch number of the parent latch
CHILD#NUMBERChild latch number (unique only to each parent latch)
LEVEL#NUMBERLatch level
NAMEVARCHAR2(64)Latch name
HASHNUMBERLatch hash
GETSNUMBERNumber of times the latch was requested in willing-to-wait mode
MISSESNUMBERNumber of times the latch was requested in willing-to-wait mode and the requester had to wait
SLEEPSNUMBERNumber of times a willing-to-wait latch request resulted in a session sleeping while waiting for the latch
IMMEDIATE_GETSNUMBERNumber of times a latch was requested in no-wait mode
IMMEDIATE_MISSESNUMBERNumber of times a no-wait latch request did not succeed (that is, missed)
WAITERS_WOKENNUMBERThis column has been deprecated and is present only for compatibility with previous releases of Oracle. No data is accumulated for this column; it will always have a value of zero.
WAITS_HOLDING_LATCHNUMBERThis column has been deprecated and is present only for compatibility with previous releases of Oracle. No data is accumulated for this column; it will always have a value of zero.
SPIN_GETSNUMBERWilling-to-wait latch requests which missed the first try but succeeded while spinning
SLEEP[1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11]NUMBERThese columns have been deprecated and are present only for compatibility with previous releases of Oracle. No data is accumulated for these columns; they will always have a value of zero. As a substitute for these columns you can query the appropriate rows of the V$EVENT_HISTOGRAM view where the EVENT column has a value of latch free or latch:%.
WAIT_TIMENUMBERElapsed time spent waiting for the latch (in microseconds)
CON_IDNUMBERThe ID of the container to which the data pertains. 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

ADDR: latch对象的物理地址。

LATCH#:子latch的父latch号。

CHILD#:子latch号,对于每一个父latch,子latch都是唯一的。

LEVEL#:latch级别。

NAME:latch名称。

HASH:latch哈希值。

GETS:在Willing-to-waits模式下请求latch次数。

MISSES在Willing-to-waits模式下发生等待时请求latch次数。

SLEEPS:当发生latch等待导致session休眠时请求latch的次数。

IMMEDIATE_GETS:no-wait模式下请求latch次数。

IMMEDIATE_MISSES:请求no-wait latch失败的次数。

WAITERS_WOKEN:该列已经被当前版本弃用,保留是为了向前兼容。

WAITS_HOLDING_LATCH该列已经被当前版本弃用,保留是为了向前兼容。

SPIN_GETS:当spinning时,最终成功请求Willing-to-wait latch次数

WAIT_TIME:latch等待消耗的时间(以微秒计算)。

CON_ID:表明数据的从属关系,0 表示那些行属于CDB的数据,1 表示仅属于root,n 表示适用的container ID。

 

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v$latch_children tc %d

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