Re: Nicer error when connecting to standby with hot_standby=off

Hi,

On 2020-03-09 18:40:32 -0400, James Coleman wrote:
> On Mon, Mar 9, 2020 at 6:28 PM Andres Freund <andres@anarazel.de> wrote:
> > > I wanted to get some initial feedback on the idea before writing a patch:
> > > does that seem like a reasonable change? Is it actually plausible to
> > > distinguish between this state and "still recovering" (i.e., when starting
> > > up a hot standby but initial recovery hasn't completed so it legitimately
> > > can't accept connections yet)? If so, should we include the possibility if
> > > hot_standby isn't on, just in case?
> >
> > Yes, it is feasible to distinguish those cases. And we should, if we're
> > going to change things around.
> 
> I'll look into this hopefully soon, but it's helpful to know that it's
> possible. Is it basically along the lines of checking to see if the
> LSN is past the minimum recovery point?

No, I don't think that's the right approach. IIRC the startup process
(i.e. the one doing the WAL replay) signals postmaster once consistency
has been achieved. So you can just use that state.

Greetings,

Andres Freund