Re: Restricting maximum keep segments by repslots

From: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
To: peter(dot)eisentraut(at)2ndquadrant(dot)com
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Restricting maximum keep segments by repslots
Date: 2017-08-28 09:36:14
Message-ID: 20170828.183614.200480339.horiguchi.kyotaro@lab.ntt.co.jp
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Hello,

I'll add this to CF2017-09.

At Mon, 06 Mar 2017 18:20:06 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote in <20170306(dot)182006(dot)172683338(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
> Thank you for the comment.
>
> At Fri, 3 Mar 2017 14:47:20 -0500, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote in <ac510b45-7805-7ccc-734c-1b38a6645f3e(at)2ndquadrant(dot)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,

Attachment Content-Type Size
slot_releaf_vent_v3.patch text/x-patch 3.0 KB

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