Re: Vacuum as "easily obtained" locks

On Wed, 2011-08-03 at 10:17 -0400, Tom Lane wrote:
> Michael Graham <mgraham(at)bloxx(dot)com> writes:
> > Would my applications
> > constant polling of the queue mean that the lock could not be easily
> > obtained?
>
> Very possible, depending on what duty cycle is involved there.

Hmm. The clients aren't that aggressive, especially when they failed to
find data on a previous select, there are 4 clients, they each poll
every 10 seconds and the select runs in <1ms.

It might be worth noting that they don't ever disconnect from the
server, but I assume that is not an issue for getting the
AccessExclusiveLock on the table?

My worry at the moment is that because the table is so large the vacuum
takes a very long time to run (one has been running for 5hrs) and I
assume it will continue to run until it is able to get the
AccessExclusiveLock is so desperately wants.

Cheers,
--
Michael Graham <mgraham(at)bloxx(dot)com>