On 2014-01-02 16:05:09 -0500, Robert Haas wrote:
> On Thu, Jan 2, 2014 at 3:19 PM, Andres Freund <andres@2ndquadrant.com> wrote:
> >> I was wondering if we could somehow arrange to not
> >> release the subtransaction's AccessShareLock on the table, as long as it
> >> was protecting toasted references someplace.
> >
> > Sounds fairly ugly...
>
> I think the only principled fixes are to either retain the lock or
> forcibly detoast before releasing it.
I don't think that's sufficient. Unless I miss something the problem
isn't restricted to TRUNCATE and such at all. I think a plain VACUUM
should be sufficient? I haven't tested it, but INSERT RETURNING
toasted_col a row, storing the result in a record, and then aborting the
subtransaction will allow the inserted row to be VACUUMed by a
concurrent transaction.
So I don't think anything along those lines will be sufficient.
Greetings,
Andres Freund
-- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services