Sorry, I misunderstood the meaning of PgStat_*.
At Fri, 11 Dec 2015 09:41:04 +0900, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote in
<566A1BA0.70707@lab.ntt.co.jp>
> > As far as I understand it, the basic reason why this patch exists is
> > to allow a DBA to have a hint of the progress of a VACUUM that may be
> > taking minutes, or say hours, which is something we don't have now. So
> > it seems perfectly fine to me to report this information
> > asynchronously with a bit of lag. Why would we need so much precision
> > in the report?
>
> Sorry, I didn't mean to overstate this requirement. I agree precise
> real-time reporting of progress info is not such a stringent requirement
> from the patch. The point regarding whether we should storm the collector
> with progress info messages still holds, IMHO.
Taking a few seconds interval between each messages would be
sufficient. I personaly think that gettimeofday() per processing
every buffer (or few buffers) is not so heavy-weight but I
suppose there's not such a consensus here. However,
IsCheckpointOnSchedule does that per writing one buffer.
vacuum_delay_point() seems to be a reasonable point to check the
interval and send stats since it would be designed to be called
with the interval also appropriate for this purpose.
regards,
--
Kyotaro Horiguchi
NTT Open Source Software Center
