Re: [HACKERS] Restricting maximum keep segments by repslots

At Fri, 22 Feb 2019 10:12:51 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote in <20190222(dot)101251(dot)03333542(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
horiguchi.kyotaro> At Fri, 15 Feb 2019 19:13:23 -0800, Andres Freund <andres(at)anarazel(dot)de> wrote in <20190216031323(dot)t7tfrae4l6zqtseo(at)alap3(dot)anarazel(dot)de>
> > Maybe I'm missing something, but how does this prevent issues with
> > active slots that are currently accessing the WAL this patch now
> > suddenly allows to be removed? Especially for logical slots that seems
> > not unproblematic?
>
> No matter whether logical or physical, when reading an
> overwritten page of a recycled/renamed segment file, page
> validation at reading-in finds that it is of a different segment
> than expected. 0006 in [1] introduces more active checking on
> that.
>
> [1] https://www.postgresql.org/message-id/20181220.162438.121484007.horiguchi.kyotaro%40lab.ntt.co.jp
>
> > Besides that, this patch needs substantial spelling / language / comment
> > polishing. Horiguchi-san, it'd probably be good if you could make a
> > careful pass, and then maybe a native speaker could go over it?
>
> Thank you for your kind suggestion. As I did for other patches,
> I'll review it by myself and come up with a new version soon.

I checked spelling comments and commit messages, then perhaps
corrected and improved them. I hope they looks nice..

0006 is separate from 0001, since I still doubt the necessity.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center