Robert Haas wrote:
> On Thu, Aug 25, 2016 at 1:43 PM, Josh Berkus <> wrote:

> > The one thing I'd be worried about with the increase in size is folks
> > using PostgreSQL for very small databases.  If your database is only
> > 30MB or so in size, the increase in size of the WAL will be pretty
> > significant (+144MB for the base 3 WAL segments).  I'm not sure this is
> > a real problem which users will notice (in today's scales, 144MB ain't
> > much), but if it turns out to be, it would be nice to have a way to
> > switch it back *just for them* without recompiling.
> I think you may be forgetting that "the base 3 WAL segments" is no
> longer the default configuration.  checkpoint_segments=3 is history;
> we now have max_wal_size=1GB, which is a maximum of 64 WAL segments,
> not 3.

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.

Álvaro Herrera      
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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