From: | Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp> |
---|---|
To: | alvherre(at)alvh(dot)no-ip(dot)org |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: obtaining row locking information |
Date: | 2005-08-12 05:08:29 |
Message-ID: | 20050812.140829.59654610.t-ishii@sra.co.jp |
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Thread: | |
Lists: | pgsql-hackers |
> On Fri, Aug 12, 2005 at 12:27:25PM +0900, Tatsuo Ishii wrote:
>
> > However even one of transactions, for example 647 commits, still it
> > shows as if 647 is a member of muitixid 3.
> >
> > test=# select * from pgrowlocks('t1');
> > locked_row | lock_type | locker | multi | xids
> > ------------+-----------+--------+-------+-----------
> > (0,1) | Shared | 3 | t | {646,647}
> > (1 row)
> >
> > Am I missing something?
>
> By design, a MultiXactId does not change its membership, that is, no
> members are added nor deleted. When this has to happen (for example a
> row is locked by another backend), a new MultiXactId is generated. The
> caller is expected to check whether the member transactions are still
> running.
But it seems when members are deleted, new multixid is not
generated. i.e. I see "locker" column does not change. Is this an
expected behavior?
--
Tatsuo Ishii
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