Re: refresh materialized view concurrently

Kevin Grittner <kgrittn(at)ymail(dot)com> writes:
> Robert Haas <robertmhaas(at)gmail(dot)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.

regards, tom lane