等待事件V$視圖

本節包含一些顯示等待事件的V$ 腳本。從個人角度來說，我更喜歡使用STATSPACK 報表、AWR 報表或企業管理器來查找等待事件。也就是說，有些很好的視圖可以查看等待事件。 Oracle 10gR2中添加了一些新的視圖，但最幸運的是在V$SESSION_WAIT中找到的東西現在在V$SESSION中可以找到。

馬上該誰等待--查詢V$SESSION_WAIT / V$SESSION

select event, sum(decode(wait_time,0,1,0)) "Waiting Now",

sum(decode(wait_time,0,0,1)) "Previous Waits",

count(*) "Total"

from v$session_wait

group by event

order by count(*);WAIT_TIME = 0 means that it's waiting

WAIT_TIME > 0 means that it previously waited this many msEVENT??????????????????????????? Waiting Now? Previous Waits Total

--------------------------- ------------ -------------- -------

db file sequential read?????? ?0????????????? 1???????????????? 1

db file scattered read??????? ?2????????????? 0???????????????? 2

latch free????????????????????? ?0??????????? ? 1???????????????? 1

enqueue???????????????????????? ? 2????????????? 0???????????????? 2

SQL*Net message from client? ?0??????????? 254???????????? ? 480

...select event, sum(decode(wait_time,0,1,0)) "Waiting Now",

sum(decode(wait_time,0,0,1)) "Previous Waits",

count(*) "Total"

from v$session

group by event

order by count(*);

EVENT??????????????????????????? ?Waiting Now Previous Waits? ??Total

--------------------------- ?------------ -------------- ???--------

db file sequential read?????? ?0????????????? 1???????????????? ???1

db file scattered read??????? ?2????????????? 0???????????????? ???2

latch free????????????????????? ?0???????????? ?1???????????????? ???1

enqueue????????????????????????? ?2????????????? 0???????????????? ???2

SQL*Net message from client? ?0????????? ? 254????????????? ??? 480

...馬上該誰等待；SPECIFIC Waits--查詢V$SESSION_WAIT

SELECT /*+ ordered */ sid, event, owner, segment_name, segment_type,p1,p2,p3

FROM?? v$session_wait sw, dba_extents de

WHERE? de.file_id = sw.p1

AND??? sw.p2 between de.block_id and de.block_id+de.blocks - 1

AND??? (event = 'buffer busy waits' OR event = 'write complete waits')

AND??? p1 IS NOT null

ORDER BY event,sid;誰在等待 - 最后10 個等待數--查詢V$SESSION_WAIT_HISTORY

SELECT /*+ ordered */ sid, event, owner, segment_name, segment_type,p1,p2,p3

FROM?? v$session_wait_history sw, dba_extents de

WHERE? de.file_id = sw.p1

AND??? sw.p2 between de.block_id and de.block_id+de.blocks - 1

AND??? (event = 'buffer busy waits' OR event = 'write complete waits')

AND??? p1 IS NOT null

ORDER BY event,sid;查找P1, P2, P3代表什么--查詢 V$EVENT_NAME

col name for a20

col p1 for a10

col p2 for a10

col p3 for a10

select event#,name,parameter1 p1,parameter2 p2,parameter3 p3

from??? v$event_name

where?? name in ('buffer busy waits', 'write complete waits');EVENT#????????? NAME??????????????????? P1?????????? P2?????????? P3

------------- -------------------- ---------- ---------- ----------

143 write complete waits file#??????? block#

145 buffer busy waits??? ?file#??????? block#???? id會話開始后的所有等待數--查詢 V$SESSION_EVENT

select ?sid, event, total_waits, time_waited, event_id

from??? ?v$session_event

where?? time_waited > 0

order ??by time_waited;SID????????? EVENT?????????????????????????????? TOTAL_WAITS? TIME_WAITED

---------- ------------------------------ ----------- -----------

159 ?process startup?????????????????????????????? 2????????????? 1

167 latch: redo allocation???????????????????? ? 4????????????? 1

168 log buffer space????????????????????????????? 2????????????? 3

166 control file single write?????????????????? 5????????????? 4

...類的所有會話等待數--查詢V$SESSION_WAIT_CLASS

select sid, wait_class, total_waits

from??? v$session_wait_class;SID WAIT_CLASS????????????? TOTAL_WAITS

---------- -------------------- -----------

168 Other??????????????????????????????? 2

168 Concurrency???????????????????????? 1

168 Idle??????????????????????????? 12825

168 User I/O?????????????????????????? 12

168 System I/O????????????????????? 4448

169 Other??????????????????????????????? 1

169 Idle??????????????????????????? 12812

170 Idle??????????????????????????? 13527系統啟動后的所有等待數--查詢V$SYSTEM_EVENT

select? event, total_waits, time_waited, event_id

from??? ?v$system_event

where?? time_waited > 0

order? ? by time_waited;EVENT???????????????????????????????????? TOTAL_WAITS TIME_WAITED??? EVENT_ID

----------------------------------- ----------- ----------- ----------

enq: TX - row lock contention???????????????? 1196?????? 366837 ???310662678

enq: TM - contention???????????????????????????? 170??????? 52074? ???668627480

db file sequential read?????????????????????? 17387???????? 3163 ??2652584166

control file parallel write??????????????? ??12961??????? 23117 ??4078387448

db file scattered read?????????????????????? ??4706??????? 15762??? 506183215

class slave wait??????????????????????????????? ???20??????? 10246 ???1055154682

類的系統等待數--查詢V$SYSTEM_WAIT_CLASS

select wait_class, total_waits

from??? v$system_wait_class

order?? by total_waits desc;WAIT_CLASS????????????? TOTAL_WAITS

-------------------- -----------

Idle????????????????????????? 161896

Other????????????????????????? 65308

System I/O??????????????????? 24339

User I/O????????????????????? 22227

Application?????????????????? 1404

Commit????????????????????????? 524

Network???????????????????????? 522

Concurrency??????????????????? 221

Configuration????????????????? ?55

...類的系統等待數--查詢V$ACTIVE_SESSION_HISTORY

--In the query below, the highest count session is leader in non-idle wait events.

select session_id,count(1)

from??? v$active_session_history

group?? by session_id

order? by 2;

In the query below, find the SQL for the leader in non-idle wait events.

select c.sql_id, a.sql_text

from v$sql a, (select sql_id,count(1)

from v$active_session_history b where sql_id is not null

group by sql_id

order by 2 desc) c

where rownum <= 5

order by rownum;

技巧：

在Oracle 10g中V$SESSION_WAIT中的所有等待事件列現在都在V$SESSION中。因此，確保查詢等待信息的 V$SESSION，因為它是一個更快的視圖。V$ACTIVE_SESSION_HISTORY (ASH)將許多重要統計數據合并為一個視圖或一個報表(ASH報表)。

總結

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