Re: refresh materialized view concurrently

On Wed, Jul 3, 2013 at 10:25 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Kevin Grittner <kgrittn@ymail.com> writes:
>> Robert Haas <robertmhaas@gmail.com> wrote:
>>> I doubt very much that this is safe.  And even if it is safe
>>> today, I think it's a bad idea, because we're likely to try to
>>> reduce lock levels in the future.  Taking no lock on a relation
>>> we're opening, even an index, seems certain to be a bad idea.
>
> I'm with Robert on this.
>
>> What we're talking about is taking a look at the index definition
>> while the indexed table involved is covered by an ExclusiveLock.
>> Why is that more dangerous than inserting entries into an index
>> without taking a lock on that index while the indexed table is
>> covered by a RowExclusiveLock, as happens on INSERT?
>
> I don't believe that that happens.  If it does, it's a bug.  Either the
> planner or the executor should be taking a lock on each index touched
> by a query.

It seems Kevin's right.  Not sure why that doesn't break.

-- 
Robert Haas
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