Re: increasing the default WAL segment size

Robert Haas wrote:
> On Thu, Aug 25, 2016 at 2:49 PM, Alvaro Herrera
> <alvherre(at)2ndquadrant(dot)com> wrote:

> > I think the relevant one for that case is the minimum, though:
> >
> > #min_wal_size = 80MB
> >
> > which corresponds to 5 segments. I suppose the default value for this
> > minimum would change to some multiple of 64MB.
>
> Yeah, Andres made the same point, although it looks like he
> erroneously stated that the minimum was 48MB whereas you have it as
> 80MB, which seems to be the actual value. I assume we would have to
> raise that to either 128MB or 192MB, which does feel like a bit of a
> hefty increase. It doesn't matter if you're going to make extensive
> use of the cluster, but if somebody's spinning up hundreds of clusters
> each of which has very little activity it might not be an altogether
> welcome change.

Yeah, and it's also related to the point Josh Berkus was making about
clusters with little activity.

Does it work to set the minimum to one WAL segment, i.e. 64MB? guc.c
has a hardcoded minimum of 2, but I couldn't find an explanation for it.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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