RE: Who Write Undo Information From The DbCache To The Physically UndoDatafile.
- From: "Christian Antognini" <Christian.Antognini@xxxxxxxxxxxx>
- To: <sheldonquinny@xxxxxxxxx>
- Date: Thu, 12 May 2005 15:51:04 +0200
Hi Sheldon
>I Would Like To Know , If Undo Block Is Brought In The Buffer Cache,
>During An Update.. SO What Process Write The Undo Block [Old Image] To
>The Physically Undo Datafile.
Just an observation...
Which processes opened the datafile of an undo tablespace?
linux:oracle:A920 /u00/app/oracle> lsof /u00/oradata/A920/undotbs01.dbf
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
oracle 18808 oracle 16uW REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 18810 oracle 17u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 18812 oracle 16u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 18814 oracle 13u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 18820 oracle 14u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 18837 oracle 16u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 18839 oracle 16u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 18841 oracle 16u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 29676 oracle 15u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
oracle 30232 oracle 14u REG 8,17 220209152 327696 =
/u00/oradata/A920/undotbs01.dbf
Ok, there are 10 processes... but if you carefully give a look to the =
output only one has a write lock on it (flag "W"), i.e. 18808.
linux:oracle:A920 /u00/app/oracle> ps -fp 18808
UID PID PPID C STIME TTY TIME CMD
oracle 18808 1 0 May11 ? 00:00:08 ora_dbw0_A920
HTH
Chris
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