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 |
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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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