Re: [PostgreSQL 10] default of hot_standby should be "on"?

On Wed, Apr 26, 2017 at 1:25 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:

> On Wed, Apr 26, 2017 at 07:33:27AM +0000, Tsunakawa, Takayuki wrote:
> > From: pgsql-hackers-owner(at)postgresql(dot)org
> > > [mailto:pgsql-hackers-owner(at)postgresql(dot)org] On Behalf Of Masahiko
> Sawada
> > > The idea of changing the default value seems good to me but I'm not
> sure
> > > it's good idea to change the default value now under the circumstances
> where
> > > we're focus on stabilization.
> > > Also we should update the document as well.
> > >
> >
> > We can consider like this: the OP found a usability problem as a result
> of PG 10 development, so we will fix it as a stabilization work.
>
> We did work in Postgres 10 to make replication simpler with better
> defaults. This would be part of that improvement.
>

+1. I definitely think we should do it, and 10 would be the time to do it.

The failure scenario is that a standby node will no longer work by default
*if* you have changed the master to minimal. But unless you have explicitly
dropped that one, it would work.

So I definitely think we should change that.

I wonder if we should also consider changing the standby error message to
be a WARNING instead of an ERROR. So that if you try to start up a standby
with hot_standby=on but master with wal_level=replica it would turn into a
cold standby.

We should change the default independently of that, I think, but it might
make sense to do both.

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>