Re: checkpoints are duplicated even while the system is idle

On Thu, Oct 6, 2011 at 5:06 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>> The current idea is that if there has been no activity then we skip
>> checkpoint. But all it takes is a single WAL record and off we go with
>> another checkpoint. If there hasn't been much WAL activity, there is
>> not much point in having another checkpoint record since there is
>> little if any time to be saved in recovery.
>
>> So why not avoid checkpoints until we have written at least 1 WAL file
>> worth of data?
>
> +1, but I think you need to compare to the last checkpoint's REDO
> pointer, not to the position of the checkpoint record itself.
> Otherwise, the argument falls down if there was a lot of activity
> during the last checkpoint (which is not unlikely in these days of
> spread checkpoints).

Agreed, that's better.

> Also I think the comment needs more extensive revision than you gave it.

OK, will do.

New version attached. Docs later.

Do we want this backpatched? If so, suggest just 9.1 and 9.0?

--
 Simon Riggs                   http://www.2ndQuadrant.com/
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