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Re: Problem with ALTER TABLE - occasional "tuple concurrently updated"

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Jon Nelson <jnelson+pgsql(at)jamponi(dot)net>, pgsql-bugs <pgsql-bugs(at)postgresql(dot)org>
Subject: Re: Problem with ALTER TABLE - occasional "tuple concurrently updated"
Date: 2010-11-18 18:35:12
Message-ID: 1290105289-sup-6685@alvh.no-ip.org (view raw or flat)
Thread:
Lists: pgsql-bugs
Excerpts from Alvaro Herrera's message of jue nov 18 15:31:16 -0300 2010:
> Excerpts from Robert Haas's message of jue nov 18 15:11:37 -0300 2010:
> 
> > In the current master branch, it appears that "ALTER TABLE c INHERIT
> > p" takes a ShareUpdateExclusiveLock on the child, which seems
> > sufficient, and an AccessShareLock on the parent, which seems like it
> > might not be; though I'm having a hard time figuring out exactly when
> > it wouldn't be, especially since in 8.4 I'm fairly sure any ALTER
> > TABLE command takes an AccessExclusiveLock.
> 
> What if two of these run at the same time, and the parent doesn't
> have children when they start?  They would both try to set
> relhassubclass, no?

Yep, duplicated the issue that way.

-- 
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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Next:From: Andrey G.Date: 2010-11-18 19:59:18
Subject: Re: BUG #5757: PL/PGSQL composite variable field error reporting
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