Re: PATCH: regular logging of checkpoint progress

On Thu, Sep 1, 2011 at 3:59 PM, Tomas Vondra <tv(at)fuzzy(dot)cz> wrote:
> I've prepared a significantly simplified version of the patch. The two
> main changes are
>
> (a) it does not update the pg_stat_bgwriter anymore, it just prints an
> info to the server log
>
> (b) a new GUC is not required, it's driven by the log_checkpoints
>
> This version will log at least 10 'checkpoint status' lines (at 10%, 20%,
> 30%, ...) and whenever 5 seconds since the last log elapses. The time is
> not checked for each buffer but for 128 buffers.
>
> So if the checkpoint is very slow, you'll get a message every 5 seconds,
> if it's fast you'll get 10 messages.

This seems like a strange heuristic. I understand the value of
emitting a progress report every N seconds, but why would you want a
report at 10%, 20%, 30% even if it hasn't been 5 seconds yet? I don't
need ten progress messages on a checkpoint that only takes three
seconds to complete.

--
Robert Haas
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