Re: patch to allow disable of WAL recycling

At Thu, 19 Jul 2018 12:37:26 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote in <20180719(dot)123726(dot)00899102(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
> At Tue, 17 Jul 2018 21:01:03 -0400, Robert Haas <robertmhaas(at)gmail(dot)com> wrote in <CA+Tgmob0hs=eZ7RquTLzYUwAuHtgORvPxjNXgifZ04he-JK7Rw(at)mail(dot)gmail(dot)com>
> > On Tue, Jul 17, 2018 at 3:12 PM, Peter Eisentraut
> > <peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> > > The actual implementation could use another round of consideration. I
> > > wonder how this should interact with min_wal_size. Wouldn't
> > > min_wal_size = 0 already do what we need (if you could set it to 0,
> > > which is currently not possible)?
> >
> > Hmm, would that actually disable recycling, or just make it happen only rarely?
>
> It doens't. Instead setting max_wal_size smaller than checkpoint
> interval should do that.

And that's wrong. It makes checkpoint unreasonably frequent.

My result is that we cannot disable recycling perfectly just by
setting min/max_wal_size.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center