Re: Remove secondary checkpoint

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Remove secondary checkpoint
Date: 2017-10-30 17:58:43
Message-ID: CANP8+jK9jkosKQS44gvf2pfaBxOc5Ef_ea3OT0=XDrcg-e20eQ@mail.gmail.com
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On 30 October 2017 at 15:22, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:

>> You forgot to update this formula in xlog.c:
>> distance = (2.0 + CheckPointCompletionTarget) * CheckPointDistanceEstimate;
>> /* add 10% for good measure. */
>> distance *= 1.10;
>> You can guess easily where the mistake is.
>
> Doh - fixed that before posting, so I must have sent the wrong patch.
>
> It's the 10%, right? ;-)

So, there are 2 locations that mention 2.0 in xlog.c

I had already fixed one, which is why I remembered editing it.

The other one you mention has a detailed comment above it explaining
why it should be 2.0 rather than 1.0, so I left it.

Let me know if you still think it should be removed? I can see the
argument both ways.

Or maybe we need another patch to account for manual checkpoints.

--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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