Re: SSX lock

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Wed, 16 Jan 2002 13:30:40 -0000
Message-ID: <1011187727.19576.0.nnrp-02.9e984b29@news.demon.co.uk>

The SSX (mode 5) lock can also appear with the PK/FK problem if the session that is updating the PK has previous updated the child table. The steps are:

update child table

acquires mode 3 on child update PK
acquires mode 3 on parent, mode 5 on child

I would guess that in your experiments you only did the update on parent.

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Jonathan Lewis
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Stephan Bressler wrote in message ...


>Hi,

>

>I've got a locking problem on 8.1.7.

>

>v$locks shows 1 session holding a lock (type 5) on table a while some other

>sessions are requesting locks(type 3) on table a.

>

>What causes type 5 (SSX) locks (beside 'lock table in share row exclusiv

>mode' statements)?

>

>Some describe problems with missing foreign key indexes. But my experiments

>show locks type 4 (shared table lock) on the child tables.

>

>TIA

>Stephan

>

>

Received on Wed Jan 16 2002 - 07:30:40 CST