From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
---|---|
To: | Stephen Frost <sfrost(at)snowman(dot)net> |
Cc: | Vik Fearing <vik(dot)fearing(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Logging idle checkpoints |
Date: | 2017-10-03 01:23:08 |
Message-ID: | CAB7nPqQ3Q1J_wBC7yPXk39dO0RGvbM4-nYp2gMrCJ7pfPJXcYw@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On Tue, Oct 3, 2017 at 12:01 AM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> I certainly don't care for the idea of adding log messages saying we
> aren't doing anything just to match a count that's incorrectly claiming
> that checkpoints are happening when they aren't.
>
> The down-thread suggestion of keeping track of skipped checkpoints might
> be interesting, but I'm not entirely convinced it really is. We have
> time to debate that, of course, but I don't really see how that's
> helpful. At the moment, it seems like the suggestion to add that column
> is based on the assumption that we're going to start logging skipped
> checkpoints and having that column would allow us to match up the count
> between the new column and the "skipped checkpoint" messages in the logs
> and I can not help but feel that this is a ridiculous amount of effort
> being put into the analysis of something that *didn't* happen.
Being able to look at how many checkpoints are skipped can be used as
a tuning indicator of max_wal_size and checkpoint_timeout, or in short
increase them if those remain idle. Since their introduction in
335feca4, m_timed_checkpoints and m_requested_checkpoints track the
number of checkpoint requests, not if a checkpoint has been actually
executed or not, I am not sure that this should be changed after 10
years. So, to put it in other words, wouldn't we want a way to track
checkpoints that are *executed*, meaning that we could increment a
counter after doing the skip checks in CreateRestartPoint() and
CreateCheckPoint()?
--
Michael
From | Date | Subject | |
---|---|---|---|
Next Message | Haribabu Kommi | 2017-10-03 01:27:05 | Re: Commitfest 201709 is now closed |
Previous Message | Michael Paquier | 2017-10-03 01:09:38 | Re: 64-bit queryId? |