Re: Vacuum as "easily obtained" locks - Mailing list pgsql-general

From Michael Graham
Subject Re: Vacuum as "easily obtained" locks
Date
Msg-id 1312383445.24461.71.camel@brutus
Whole thread Raw
In response to Re: Vacuum as "easily obtained" locks  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Vacuum as "easily obtained" locks  (Pavan Deolasee <pavan.deolasee@gmail.com>)
Re: Vacuum as "easily obtained" locks  (Scott Marlowe <scott.marlowe@gmail.com>)
Re: Vacuum as "easily obtained" locks  (Bill Moran <wmoran@potentialtech.com>)
Re: Vacuum as "easily obtained" locks  (Jerry Sievers <gsievers19@comcast.net>)
List pgsql-general
On Wed, 2011-08-03 at 10:17 -0400, Tom Lane wrote:
> Michael Graham <mgraham@bloxx.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@bloxx.com>



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