关于AWR的Undo Segment Stats
Snap Id Snap Time Sessions Curs/Sess--------- ------------------- -------- ---------
Begin Snap: 17376 07-May-13 03:59:49 119 4.8
End Snap: 17377 07-May-13 04:27:33 111 5.7
Elapsed: 27.73 (mins)
DB Time: 572.22 (mins)
Load Profile
~~~~~~~~~~~~ Per Second Per Transaction
--------------- ---------------
Redo size: 2,021,766.94 924,625.49
Logical reads: 179,092.57 81,905.36
Block changes: 9,351.61 4,276.82
Physical reads: 745.17 340.79
Physical writes: 617.94 282.60
User calls: 19.79 9.05
Parses: 346.01 158.24
Hard parses: 3.79 1.74
Sorts: 65.49 29.95
Logons: 2.87 1.31
Executes: 431.35 197.27
Transactions: 2.19
在Load Profile可以看到每秒的事务数只有2个。
Undo Segment Summary DB/Inst: ZTEDM2/ztedm2 Snaps: 17376-17377
-> Min/Max TR (mins) - Min and Max Tuned Retention (minutes)
-> STO - Snapshot Too Old count, OOS - Out of Space count
-> Undo segment block stats:
-> uS - unexpired Stolen, uR - unexpired Released, uU - unexpired reUsed
-> eS - expired Stolen, eR - expired Released, eU - expired reUsed
Undo Num Undo Number of Max Qry Max Tx Min/Max STO/ uS/uR/uU/
TS# Blocks (K) Transactions Len (s) Concurcy TR (mins) OOS eS/eR/eU
---- ---------- --------------- -------- -------- --------- ----- --------------
20 211.4 258,223 15,668 34 223.76666 0/0 0/0/0/0/0/0
-------------------------------------------------------------
Undo Segment Stats DB/Inst: ZTEDM2/ztedm2 Snaps: 17376-17377
-> Most recent 35 Undostat rows, ordered by Time desc
Num Undo Number of Max Qry Max Tx Tun Ret STO/ uS/uR/uU/
End Time Blocks Transactions Len (s) Concy (mins) OOS eS/eR/eU
------------ ----------- ------------ ------- ------- ------- ----- ------------
07-May 04:20 40,922 35,144 15,668 18 240 0/0 0/0/0/0/0/0
07-May 04:10 98,865 153,507 15,062 22 231 0/0 0/0/0/0/0/0
07-May 04:00 71,577 69,572 14,456 34 224 0/0 0/0/0/0/0/0
-------------------------------------------------------------
但是在Undo Segment Stats的Number of Transactions列显示的事务数确大得多，这是为什么呢？ 说明有很多长事务 很有多低效率事务运行不完，这种情况数据库基本hang了
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