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Oracle V$SESSION_WAIT

原创 Linux操作系统 作者:zecaro 时间:2011-04-03 21:54:20 0 删除 编辑

Oracle® Database Reference10g Release 2 (10.2)  Part Number   B14237-04

    在10gr2中,V$SESSION_WAIT的所有内容都可以在v$session中看到。

V$SESSION_WAIT displays the resources or events for which active sessions are waiting.

V$SESSION_WAIT展示了active的session等待的resources or events 。

The following are tuning considerations:

  • P1RAW, P2RAW, and P3RAW display the same values as the P1, P2, and P3 columns, except that the numbers are displayed in hexadecimal.

P1RAW, P2RAW, and P3RAWP1, P2, and P3 的十六进制表示

  • The WAIT_TIME column contains a value of -2 on platforms that do not support a fast timing mechanism. If you are running on one of these platforms and you want this column to reflect true wait times, then you must set the TIMED_STATISTICS initialization parameter to true. Remember that doing this has a small negative effect on system performance.

WAIT_TIME =-2表示所在平台不支持 fast timing mechanism。如果想要此列显示等待时间,必须将TIMED_STATISTICS 设置为ture。这将对系统系能带来一些微小的副作用。

In previous releases, the WAIT_TIME column contained an arbitrarily large value instead of a negative value to indicate the platform. did not have a fast timing mechanism.

在更早的版本,WAIT_TIME 列使用一个非常大的值来表示所在平台不支持 fast timing mechanism,而不是负数(如前所述)。

  • The STATE column interprets the value of WAIT_TIME and describes the state of the current or most recent wait.

 STATE列的数值将影响WAIT_TIME 表达的含义,并且STATE列表示当前状态还是最近一次等待。

Column Datatype Description
SID NUMBER Session identifier
SEQ# NUMBER Sequence number that uniquely identifies this wait. Incremented for each wait.
EVENT VARCHAR2(64) Resource or event for which the session is waiting

See Also: Appendix C, "Oracle Wait Events"

P1TEXT VARCHAR2(64) Description of the first additional parameter
P1 NUMBER First additional parameter
P1RAW RAW(4) First additional parameter
P2TEXT VARCHAR2(64) Description of the second additional parameter
P2 NUMBER Second additional parameter
P2RAW RAW(4) Second additional parameter
P3TEXT VARCHAR2(64) Description of the third additional parameter
P3 NUMBER Third additional parameter
P3RAW RAW(4) Third additional parameter
WAIT_CLASS_ID NUMBER Identifier of the wait class
WAIT_CLASS# NUMBER Number of the wait class
WAIT_CLASS VARCHAR2(64) Name of the wait class
WAIT_TIME NUMBER

A nonzero value is the session's last wait time. A zero value means the session is currently waiting.

非零值表示上一次等待时间;等于零时表示正在等待。

SECONDS_IN_WAIT NUMBER

If WAIT_TIME = 0, then SECONDS_IN_WAIT is the seconds spent in the current wait condition. If WAIT_TIME > 0, then SECONDS_IN_WAIT is the seconds since the start of the last wait, and SECONDS_IN_WAIT - WAIT_TIME / 100 is the active seconds since the last wait ended.

wait_time=0,表示正在等待的已经花费的时间(单位:秒)。wait_time>0,表示距离上次等待开始的时间(单位:秒)。而SECONDS_IN_WAIT - WAIT_TIME / 100表示自从上次等待后结束后的active的时间(单位:秒)。

STATE VARCHAR2(19) Wait state:
  • 0 - WAITING (the session is currently waiting)

0 表示正在等待。

  • -2 - WAITED UNKNOWN TIME (duration of last wait is unknown)

-2表示上次等待时间未知。

  • -1 - WAITED SHORT TIME (last wait <1/100th of a second)

-1表示上次等待时间很短,小于百分之一秒。

  • >0 - WAITED KNOWN TIME (WAIT_TIME = duration of last wait)

>0表示上次等待时间。


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