轉 v$session_longops視圖
阿新 • • 發佈：2017-12-17
cover var desc context lec sql_id nts parameter inpu
轉http://www.dbdream.com.cn/2013/10/14/vsession_longops%E8%A7%86%E5%9B%BE/
1.有的時候不準確 ，我看到 session wait event 一直在變化 ，也是 active 的 ，運行 時間也是48小時 以上 。但是 在 v$session_longops 顯示為totalwork =0 , 無法觀察 。是一條3000w 記錄的update. 所以只能看v$transaction.
2.
對大部分DBA來說，V$SESSION_LONGOPS視圖都不會陌生，以前在面試的時候，也有一些企業會問到如何查詢數據庫中運行時間比較長的SQL，就可以通過這個視圖來查看。
V$SESSION_LONGOPS視圖不但可以監控運行式時間比較長的SQL，也會記錄RMAN備份、EXP/EXPDP、收集統計信息、排序等操作，基本數據庫所有運行時間超過6秒的SQL都會記錄在這個視圖中，也有的DBA會定期檢查這個視圖來尋找可優化的SQL。
下面是這個視圖的結構：
01 |
SQL> desc v$session_longops |
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名稱 是否為空? 類型 註釋 |
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----------------------------------------- -------- ------------------ ------------------ |
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SID NUMBER 和V$SESSION中的SID一樣 |
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SERIAL# NUMBER 和V$SESSION中的SERIAL#一樣 |
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OPNAME VARCHAR2(64) 操作的名稱，如全表掃描 |
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TARGET VARCHAR2(64) 被操作的對象名，如表名 |
08 |
TARGET_DESC VARCHAR2(32) TARGET的描述 |
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SOFAR NUMBER 以完成的數量，如掃描多少數據塊 |
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TOTALWORK NUMBER 一共需要完成的數量 |
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UNITS VARCHAR2(32) 計量單位 |
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START_TIME DATE 開始時間 |
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LAST_UPDATE_TIME DATE 最後一次調用set_session_longops的時間 |
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TIMESTAMP DATE 特定操作的時間戳 |
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TIME_REMAINING NUMBER 預計剩余時間，單位秒 |
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ELAPSED_SECONDS NUMBER 開始操作到最後更新的時間 |
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CONTEXT NUMBER |
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MESSAGE VARCHAR2(512) 對操作的描述 |
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USERNAME VARCHAR2(30) 操作用戶的名字 |
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SQL_ADDRESS RAW(4) 用於關聯V$SQL等視圖 |
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SQL_HASH_VALUE NUMBER 用於關聯V$SQL等視圖 |
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SQL_ID VARCHAR2(13) 用於關聯V$SQL等視圖 |
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SQL_PLAN_HASH_VALUE NUMBER 用於關聯V$SQL等視圖 |
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SQL_EXEC_START DATE SQL開始運行的時間 |
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SQL_EXEC_ID NUMBER SQL執行的標識符 |
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SQL_PLAN_LINE_ID NUMBER SQL執行計劃相關 |
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SQL_PLAN_OPERATION VARCHAR2(30) SQL執行計劃相關 |
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SQL_PLAN_OPTIONS VARCHAR2(30) SQL執行計劃相關 |
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QCSID NUMBER 並行查詢 |
下面簡單做幾個超過6秒的操作，來查看下這個視圖。
先測試下insert操作。
01 |
SQL> create table longops_test as select * from dba_objects; |
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表已創建。 |
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SQL> insert into longops_test select * from longops_test; |
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已創建65525行。 |
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SQL> / |
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已創建131050行。 |
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SQL> / |
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已創建262100行。 |
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SQL> / |
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已創建524200行。 |
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SQL> / |
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已創建1048400行。 |
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SQL> commit; |
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提交完成。 |
現在INSERT操作已經超過6秒，查詢下V$SESSION_LONGOPS視圖。
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SID SERIAL# OPNAME TARGET SOFAR TOTALWORK UNITS MESSAGE SQL_PLAN_OPERATION SQL_PLAN_OPTIONS |
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--- ------- --------- ---------------- ----- -------- ----- --------------- ------------------- --------------- |
3 |
194 12 Table Scan SYS.LONGOPS_TEST 14895 14895 Blocks Table Scan: TABLE ACCESS FULL |
4 |
SYS.LONGOPS_TEST: |
5 |
14895 out of |
6 |
14895 Blocks done |
這是已經運行結束的INSERT操作，可見SOFAR和TOTALWORK的值是一樣的，在看下沒運行完的SQL。
1 |
SQL> create table longops_ctas as select * from longops_test; |
在SQL執行6秒後(還沒運行完)時，看下V$SESSION_LONGOPS視圖的狀態。
01 |
SID SERIAL# OPNAME TARGET SOFAR TOTALWORK UNITS MESSAGE SQL_PLAN_OPERATION SQL_PLAN_OPTIONS |
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--- ------- --------- ---------------- ----- -------- ----- --------------- ------------------- --------------- |
03 |
194 12 Table Scan SYS.LONGOPS_TEST 14895 14895 Blocks Table Scan: TABLE ACCESS FULL |
04 |
SYS.LONGOPS_TEST: |
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14895 out of |
06 |
14895 Blocks done |
07 |
194 12 Table Scan SYS.LONGOPS_TEST 13275 29785 Blocks Table Scan: TABLE ACCESS FULL |
08 |
SYS.LONGOPS_TEST: |
09 |
13275 out of |
10 |
29785 Blocks done |
可見，當前掃描了13275個數據塊，總共需要掃描29785個數據塊。RMAN備份和收集統計信息也同樣會被這個視圖記錄。
01 |
OPNAME SOFAR TOTALWORK MESSAGE |
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--------------------------------- ---------- ---------- ------------------------------------------- |
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Gather Table Partition Statistics 1 1 Gather Table Partition Statistics: Table |
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WR H$_OSSTAT : 1 out of 1 Partitions done |
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RMAN: aggregate input 1181953 1181953 RMAN: aggregate input: backup 33: 1181953 |
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out of 1181953 Blocks done |
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RMAN: aggregate input 1181953 1181953 RMAN: aggregate input: backup 33: 1181953 |
08 |
out of 1181953 Blocks done |
09 |
RMAN: aggregate output 359461 359461 RMAN: aggregate output: backup 33: 359461 |
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out of 359461 Blocks done |
11 |
RMAN: full datafile backup 1181280 1181280 RMAN: full datafile backup: Set Count 18: |
12 |
1181280 out of 1181280 Blocks done |
下面是ORACLE官方文檔對V$SESSION_LONGOPS視圖的介紹：
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V$SESSION_LONGOPS 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. |
02 |
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To monitor query execution progress, you must be using the cost-based optimizer and you must: |
04 |
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?Set the TIMED_STATISTICS or SQL_TRACE parameters to true |
06 |
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?Gather statistics for your objects with the DBMS_STATS package |
08 |
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You can add information to this view about application-specific long-running operations by using the DBMS_APPLICATION_INFO.SET_SESSION_LONGOPS procedure. |
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Column Datatype Description |
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------------------- ---------- --------------------------------------------------------------------------------- |
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SID NUMBER Identifier of the session processing the long-running operation. If multiple sessi |
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ons are cooperating in the long-running operation, then SID corresponds to the mai |
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n or master session. |
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SERIAL# NUMBER Serial number of the session processing the long-running operation. If multiple se |
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ssions are cooperating in the long-running operation, then SERIAL# corresponds to |
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the main or master session. SERIAL# is used to uniquely identify a session‘s objec |
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ts. Guarantees that session-level commands are applied to the correct session obje |
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cts if the session ends and another session begins with the same session ID. |
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OPNAME VARCHAR2(64) Brief description of the operation |
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TARGET VARCHAR2(64) Object on which the operation is carried out |
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TARGET_DESC VARCHAR2(32) Description of the target |
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SOFAR NUMBER Units of work done so far |
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TOTALWORK NUMBER Total units of work |
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UNITS VARCHAR2(32) Units of measurement |
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START_TIME DATE Starting time of the operation |
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LAST_UPDATE_TIME DATE Time when statistics were last updated for the operation |
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TIMESTAMP DATE Timestamp specific to the operation |
29 |
TIME_REMAINING NUMBER Estimate (in seconds) of time remaining for the operation to complete |
30 |
ELAPSED_SECONDS NUMBER Number of elapsed seconds from the start of the operations |
31 |
CONTEXT NUMBER Context |
32 |
MESSAGE VARCHAR2(512) Statistics summary message |
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USERNAME VARCHAR2(30) User ID of the user performing the operation |
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SQL_ADDRESS RAW(4 | 8) Used with the value of the SQL_HASH_VALUE column to identify the SQL statement as |
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sociated with the operation |
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SQL_HASH_VALUE NUMBER Used with the value of the SQL_ADDRESS column to identify the SQL statement assoc |
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iated with the operation |
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SQL_ID VARCHAR2(13) SQL identifier of the SQL statement associated with the long operation, if any |
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SQL_PLAN_HASH_VALUE NUMBER SQL plan hash value; NULL if SQL_ID is NULL |
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SQL_EXEC_START DATE Time when the execution of the SQL started; NULL if SQL_ID is NULL |
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SQL_EXEC_ID NUMBER SQL execution identifier (see V$SQL_MONITOR) |
42 |
SQL_PLAN_LINE_ID NUMBER SQL plan line ID corresponding to the long operation; NULL if the long operation |
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is not associated with a line of the execution plan |
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SQL_PLAN_OPERATION VARCHAR2(30) Plan operation name; NULL if SQL_PLAN_LINE_ID is NULL |
45 |
SQL_PLAN_OPTIONS VARCHAR2(30) Plan operation options; NULL if SQL_PLAN_LINE_ID is NULL |
46 |
QCSID NUMBER Session identifier of the parallel coordinator |
轉 v$session_longops視圖