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

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.

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Álvaro Herrera <alvherre@commandprompt.com>
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