動態性能視圖v$session_longops

v$session_longops

 

This view displays the status of various operations that run for longer than 6 seconds (in absolute time). These operations currently include many backup and recovery functions, statistics gathering, and query execution, and more operations are added for every Oracle release.

 

To monitor query execution progress, you must be using the cost-based optimizer and you must:

 

• Set the TIMED_STATISTICS or SQL_TRACE parameter to true

• Gather statistics for your objects with the ANALYZE statement or the DBMS_STATS package

 

該視圖記錄了執行時間長於6秒的某個操作(這些操作可能是備份，恢復，收集統計信息，Hash Join,Sort ,Nested loop，Table Scan, Index Scan 等等)，這個視圖通常用來分析SQL運行緩慢的原因，配合V$SESSION視圖。

1.必須將初始化參數 timed_statistics設置為true或者開啟sql_trace

 

2.必須用ANALYZE或者DBMS_STATS對對象收集過統計信息

 

 

Column	Datatype	Description
SID	NUMBER	Session identifier
SERIAL#	NUMBER	Session serial number
OPNAME	VARCHAR2(64)	Brief description of the operation
TARGET	VARCHAR2(64)	The object on which the operation is carried out
TARGET_DESC	VARCHAR2(32)	Description of the target
SOFAR	NUMBER	The units of work done so far
TOTALWORK	NUMBER	The total units of work
UNITS	VARCHAR2(32)	The units of measurement
START_TIME	DATE	The starting time of operation
LAST_UPDATE_TIME	DATE	Time when statistics last updated
TIMESTAMP	DATE	Timestamp
TIME_REMAINING	NUMBER	Estimate (in seconds) of time remaining for the operation to complete
ELAPSED_SECONDS	NUMBER	The number of elapsed seconds from the start of operations
CONTEXT	NUMBER	Context
MESSAGE	VARCHAR2(512)	Statistics summary message
USERNAME	VARCHAR2(30)	User ID of the user performing the operation
SQL_ADDRESS	RAW(4 | 8)	Used with the value of the SQL_HASH_VALUE column to identify the SQL statement associated with the operation
SQL_HASH_VALUE	NUMBER	Used with the value of the SQL_ADDRESS column to identify the SQL statement associated with the operation
SQL_ID	VARCHAR2(13)	SQL identifier of the SQL statement associated with the operation
QCSID	NUMBER	Session identifier of the parallel coordinator

 

 SID                    Session標識              
 SERIAL#                Session串號              
 OPNAME                 操作簡要說明           　  
 TARGET                 操作運行所在的對象          
 TARGET_DESC            目標對象說明      　　　　  
 SOFAR                  至今為止完成的工作量    　　 
 TOTALWORK              總工作量    　　　　　　　　 
 UNITS                  工作量單位            　　 
 START_TIME             操作開始時間          　　
 LAST_UPDATE_TIME       統計項最后更新時間     　　
 TIMESTAMP              操作的時間戳              
 TIME_REMAINING         預計完成操作的剩余時間(秒)   
 ELAPSED_SECONDS        從操作開始總花費時間(秒)　　 
 CONTEXT                前后關系    　　　　　　　　 
 MESSAGE                統計項的完整描述       　　
 USERNAME               執行操作的用戶ID       　　 
 SQL_ADDRESS            關聯v$sql                
 SQL_HASH_VALUE         關聯v$sql       　　　　　　
 SQL_ID                 關聯v$sql　　 　　　　
 QCSID 　　　　　　　　　　主要是並行查詢一起使用　

要理解的就是：比如某個SQL語句執行時間比較長，但是每個操作都沒有超過6秒鍾，那么你在V$SESSION_LONGOPS這個視圖中就無法查詢到該信息。

• 相關操作語句：

　　　　

SELECT USERNAME,
       SID,
       OPNAME,
       ROUND(SOFAR * 100 / TOTALWORK, 0) || '%' AS PROGRESS,
       TIME_REMAINING,
       SQL_TEXT
  FROM V$SESSION_LONGOPS, V$SQL
 WHERE TIME_REMAINING <> 0
   AND SQL_ADDRESS = ADDRESS
   AND SQL_HASH_VALUE = HASH_VALUE;

 

select * from v$session a,v$session_longops b where a.SID = b.SID and a.SERIAL# = b.SERIAL# ;  

select * from v$sql a,v$session_longops b where a.SQL_ID = b.SQL_ID ;  

select * from v$sqlarea a,v$session_longops b where a.HASH_VALUE = b.SQL_HASH_VALUE ;  

如果是在RAC,改成GV$SESSION_LONGOPS這個視圖