Re: [HACKERS] Remove secondary checkpoint

On Wed, Nov 8, 2017 at 2:23 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On 31 October 2017 at 12:01, Michael Paquier <michael.paquier@gmail.com> wrote:
>> While the mention about a manual checkpoint happening after a timed
>> one will cause a full range of WAL segments to be recycled, it is not
>> actually true that segments of the prior's prior checkpoint are not
>> needed, because with your patch the segments of the prior checkpoint
>> are getting recycled. So it seems to me that based on that the formula
>> ought to use 1.0 instead of 2.0...
>
> I think the argument in the comment is right, in that
> CheckPointDistanceEstimate is better if we use multiple checkpoint
> cycles.

Yes, the theory behind is correct. No argument behind that.

> But the implementation of that is bogus and multiplying by 2.0
> wouldn't make it better if CheckPointDistanceEstimate is wrong.

Yes, this is wrong. My apologies if my words looked confusing. By
reading your message I can see that our thoughts are on the same page.
-- 
Michael


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