Re: Restricting maximum keep segments by repslots

Hello,

I'll add this to CF2017-09.

At Mon, 06 Mar 2017 18:20:06 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> wrote in <20170306.182006.172683338.horiguchi.kyotaro@lab.ntt.co.jp>
> Thank you for the comment.
> 
> At Fri, 3 Mar 2017 14:47:20 -0500, Peter Eisentraut <peter.eisentraut@2ndquadrant.com> wrote in <ac510b45-7805-7ccc-734c-1b38a6645f3e@2ndquadrant.com>
> > On 3/1/17 19:54, Kyotaro HORIGUCHI wrote:
> > >> Please measure it in size, not in number of segments.
> > > It was difficult to dicide which is reaaonable but I named it
> > > after wal_keep_segments because it has the similar effect.
> > > 
> > > In bytes(or LSN)
> > >  max_wal_size
> > >  min_wal_size
> > >  wal_write_flush_after
> > > 
> > > In segments
> > >  wal_keep_segments
> > 
> > We have been moving away from measuring in segments.  For example,
> > checkpoint_segments was replaced by max_wal_size.
> > 
> > Also, with the proposed patch that allows changing the segment size more
> > easily, this will become more important.  (I wonder if that will require
> > wal_keep_segments to change somehow.)
> 
> Agreed. It is 'max_slot_wal_keep_size' in the new version.
> 
> wal_keep_segments might should be removed someday.

- Following to min/max_wal_size, the variable was renamed to
  "max_slot_wal_keep_size_mb" and used as ConvertToXSegs(x)"

- Stopped warning when checkpoint doesn't flush segments required
  by slots even if max_slot_wal_keep_size have worked.

- Avoided subraction that may be negative.

regards,