From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
---|---|
To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
Cc: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Proposal: Log inability to lock pages during vacuum |
Date: | 2014-11-10 18:36:55 |
Message-ID: | 20141110183655.GD1791@alvin.alvh.no-ip.org |
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Lists: | pgsql-hackers |
Andres Freund wrote:
> On 2014-11-10 14:28:30 -0300, Alvaro Herrera wrote:
> > If what we want is to quantify the extent of the issue, would it be more
> > convenient to save counters to pgstat? Vacuum already sends pgstat
> > messages, so there's no additional traffic there.
>
> I'm pretty strongly against that one in isolation. They'd need to be
> stored somewhere and they'd need to be queryable somewhere with enough
> context to make sense. To actually make sense of the numbers we'd also
> need to report all the other datapoints of vacuum in some form. That's
> quite a worthwile project imo - but *much* *much* more work than this.
We already have "last_autovacuum" columns and such in pg_stat_tables et
al, which only record the last value. My thinking regarding such
numbers is that you would save histories and put them in a chart, see
how they evolve with time. I doubt the individual numbers are worth
much, but the trends might show something interesting. As far as I
know, this is already true for most other pgstat values, with exception
of things such as live_tuples which are absolute numbers rather than
running counters.
I agree having more vacuuming data in general is a worthwhile project,
much larger than this one. Wasn't Greg Smith working on that?
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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