Re: increasing the default WAL segment size

On 2016-09-20 16:05:44 -0400, Robert Haas wrote:
> On Tue, Sep 20, 2016 at 2:49 PM, Peter Eisentraut
> <peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> > On 8/24/16 9:31 PM, Robert Haas wrote:
> >> I'd like to propose that we increase the default WAL segment size,
> >> which is currently 16MB.
> >
> > While the discussion about the best default value is ongoing, maybe we
> > should at least *allow* some larger sizes, for testing out. Currently,
> > configure says "Allowed values are 1,2,4,8,16,32,64.". What might be a
> > good new upper limit?

I'm doubtful it's worth increasing this.

> 1GB?

That sounds way too big to me. WAL file allocation would trigger pretty
massive IO storms during zeroing, max_wal_size is going to be hard to
tune, the amounts of dirty data during bulk loads is going to be very
hard to control. If somebody wants to do something like this they
better be well informed enough to override a #define.

Andres