Re: TX locks

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Fri, 28 May 2004 07:34:52 +0100
Message-ID: <00e601c4447d$e230db70$7102a8c0@Primary>

You're thinking of the 'unindexed foreign key' anomaly. You can get TX/4 locks even when there is a foreign key index.

session 1: insert new child for parent X session 2: delete parent X

Session 2 waits for session 1 to commit.

Regards

Jonathan Lewis

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

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Original Message ----- From: "Bobak, Mark" <Mark.Bobak_at_il.proquest.com> To: <oracle-l_at_freelists.org> Sent: Thursday, May 27, 2004 11:01 PM Subject: RE: TX locks

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

-----Original Message-----

From: oracle-l-bounce_at_freelists.org on behalf of Jonathan Lewis Sent: Thu 5/27/2004 3:50 PM
To: oracle-l_at_freelists.org
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.

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Received on Fri May 28 2004 - 01:31:43 CDT