RE: Reading UNDO and displaying it in v$session
- From: "Milen Kulev" <makulev@xxxxxxx>
- To: <Brandon.Allen@xxxxxxxxxxx>, <kylelf@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 3 Apr 2008 20:28:09 +0200
Hello Brandon,
yes, I am aware of this fact , but my goal was (and is) to write a performance
monitoring skript that provides me with
the infomation
about sessions details (SID, SPID, WAIT EVENT , Session State, SQL_ID, CHILD_NR
tomention a few) and object_id of
the the database object beining accesed at the moment.
The link below describes actually (this is my understanding, at least) the
dependency of ROW_WAIT_ROW# on
ROW_WAIT_OBJ#.
Perhaps ROW_WAIT_ROW# is interesting (in combination witn ROW_WAIT_OBJ# and
the other ROW_WAIT_*# from V$session) when
EVENT='enq: TX - row lock contention' ?
Best Regards. Milen
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Allen, Brandon
Sent: Thursday, April 03, 2008 6:33 PM
To: makulev@xxxxxxx; kylelf@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: Reading UNDO and displaying it in v$session
Hi Milen,
I believe the purpose of row_wait_obj#, and the other row_wait columns is only
to report relevant information when a
session is waiting on a blocking lock, i.e. the "enqueue" wait event for a TX
(aka Transaction) lock. Here are the
column descriptions from the documentation:
<http://stanford.edu/dept/itss/docs/oracle/10g/server.101/b10755/dynviews_2073.htm>
http://stanford.edu/dept/itss/docs/oracle/10g/server.101/b10755/dynviews_2073.htm
Please note the following:
ROW_WAIT_ROW# - Current row being locked. This column is valid only if the
session is currently waiting for another
transaction to commit and the value of ROW_WAIT_OBJ# is not -1. (emphasis mine)
Regards,
Brandon
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