Re: More vacuum stats

Magnus Hagander <magnus(at)hagander(dot)net> writes:
> On Sun, Aug 22, 2010 at 17:29, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> So I'd like to see a positive argument why this is important for users
>> to know, rather than merely "we should expose every conceivable detail
>> by default". Why wouldn't a user care more about last AV time for a
>> specific table, which we already do expose?

> You need to connect to every database to do that. If you have many
> databases, that's a lot of overhead particularly if you're doing tihs
> for regular monitoring. Plus, those views will only track when
> autovacuum actually *did* something.

Well, the last-launch-time doesn't prove that autovacuum actually *did*
something ;-).

> Being able to see that autovacuum hasn't even touched a database for
> too long would be an early-indicator that you have some issues with
> it.

With the current AV launch algorithm, unless you have very serious
system-wide issues there will be a worker launched into each database
approximately every autovacuum_naptime seconds. AFAICS this does not
tell you anything interesting about whether AV is getting its work done.

regards, tom lane