RE: TX locks

  • From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 27 May 2004 18:01:39 -0400

Jonathan,
Wouldn't PK/FK activity result in TM waits, rather than TX waits?


-----Original Message-----
From:   oracle-l-bounce@xxxxxxxxxxxxx on behalf of Jonathan Lewis
Sent:   Thu 5/27/2004 3:50 PM
To:     oracle-l@xxxxxxxxxxxxx
Cc:     
Subject:        Re: TX locks
Other common causes of TX/4 waits on a TX/6

Bitmap indexes on OLTP tables - with updates to
the bitmapped column, or inserts/delete of rows.

Updates colliding on rows in IOTs.

Several variations of pk/fk activity split across
two sessions.



Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk

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----- Original Message ----- 
From: "Adams, Matthew (GE Consumer & Industrial)" <MATT.ADAMS@xxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Thursday, May 27, 2004 7:45 PM
Subject: RE: TX locks


The blocker has the TX enqueue with lmode=3D6, the requestor=20
is requesting a shared lock (lmode=3D4). =20

I've narrowed the issue down to two the same two possibilities
you mentioned:

1)  The blocked transaction is attempting to insert the same PK/UK
values and is waiting to see if the first one commits or rolls back.

2)  Lack of an available ITL slot in either the table or index. =20
Since maxtrans is set to 255, I'm leaning away from this, although
I am aware of the fact that if there is not enough space in the block=20
to increase the ITL from the default of one, it will wait rather than
expand the ITL, eventually timing out with this 2049 error.  I think it =
would
be happening a little less frequently if this were the problem.



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