Re: Let PostgreSQL's On Schedule checkpoint write buffer smooth spread cycle by tuning IsCheckpointOnSchedule?

On 13 May 2015 at 09:35, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:

> In summary, the X^1.5 correction seems to work pretty well. It doesn't
> completely eliminate the problem, but it makes it a lot better.
>

Agreed

> I don't want to over-compensate for the full-page-write effect either,
> because there are also applications where that effect isn't so big. For
> example, an application that performs a lot of updates, but all the updates
> are on a small number of pages, so the full-page-write storm immediately
> after checkpoint doesn't last long. A worst case for this patch would be
> such an application - lots of updates on only a few pages - with a long
> checkpoint_timeoout but relatively small checkpoint_segments, so that
> checkpoints are always driven by checkpoint_segments. I'd like to see some
> benchmarking of that worst case before committing anything like this.
>

We could do better, but that is not a reason not to commit this, as is.
Commit, please.

This has been in place for a while and still remains: TODO: reduce impact
of full page writes

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