Oracle 视图 V$SESSION_WAIT 官方解释,作用,如何使用详细说明
本站中文解释
Oracle视图V$SESSION_WAIT就是用来呈现有关数据库会话当前存在的各种等待事件的视图。它有些列信息来描述会话的等待事件,例如:实例编号、会话编号、服务名称、等待状态、等待时间、相关回话资源要求、服务模块名称等。通过V$SESSION_WAIT视图,可以帮助DBA跟踪和分析会话的等待事件,检查数据库会话是否在处理正常。
使用方法:
1. 查询会话持续等待的时间超过5分钟的等待事件:
SELECT * FROM V$SESSION_WAIT WHERE time_waited > 300;
2. 查询同一个等待事件的总等待时间:
SELECT event, SUM(time_waited) FROM V$SESSION_WAIT GROUP BY event;
官方英文解释
V$SESSION_WAIT
displays the current or last wait for each session.
Column | Datatype | Description |
---|---|---|
|
|
Session identifier; maps to |
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|
A number that uniquely identifies the current or last wait (incremented for each wait) |
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If the session is currently waiting, then the resource or event for which the session is waiting. If the session is not in a wait, then the resource or event for which the session most recently waited. See Also: “Oracle Wait Events” |
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Description of the first wait event parameter |
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First wait event parameter (in decimal) |
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First wait event parameter (in hexadecimal)Foot 1 |
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Description of the second wait event parameter |
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Second wait event parameter (in decimal) |
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Second wait event parameter (in hexadecimal)Foot 1 |
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Description of the third wait event parameter |
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Third wait event parameter (in decimal) |
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Third wait event parameter (in hexadecimal)Foot 1 |
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|
Identifier of the class of the wait event |
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|
Number of the class of the wait event |
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|
Name of the class of the wait event |
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If the session is currently waiting, then the value is
This column has been deprecated in favor of the columns |
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If the session is currently waiting, then the value is the amount of time waited for the current wait. If the session is not in a wait, then the value is the amount of time since the start of the last wait. This column has been deprecated in favor of the columns |
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Wait state:
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Amount of time waited (in microseconds). If the session is currently waiting, then the value is the time spent in the current wait. If the session is currently not in a wait, then the value is the amount of time waited in the last wait. |
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Value is interpreted as follows:
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Total time for the current wait (in microseconds) A wait includes code within its beginning and end that can encounter other waits as part of its implementation. For example, a wait might need to acquire a latch to check state to determine when the wait is satisfied, and the latch itself might enter a wait. In this case, when the latch wait ends and returns to the outer wait, the latch time is included in the value of this column, while the value of |
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Heuristic wait time (in microseconds) This value is calculated by attempting to group sequential waits that appear to be the same. |
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Time elapsed since the end of the last wait (in microseconds). If the session is currently in a wait, then the value is |
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The ID of the container to which the data pertains. Possible values include:
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Footnote 1
The P1RAW
, P2RAW
, and P3RAW
columns display the same values as the P1
, P2
, and P3
columns, except that the numbers are displayed in hexadecimal.
Footnote 2 This column is available starting with Oracle Database 21c.
See Also:
“TIMED_STATISTICS” and “Oracle Wait Events”