Re: allow online change primary_conninfo

On Mon, Feb 18, 2019 at 12:06:05AM +0300, Sergei Kornilov wrote:
> Ok. This was not mentioned before Michael response
> yesterday. restore_command is much faster compared to database
> restart [...]

The startup process would not switch back to streaming with archiving
enabled until it has consumed all the segments available.  I recall
David Steele mentioning me that a perl command invocation can take
easily 100ms.  On a system which generates more than 10 segments per
segment, you can guess what happens..  I think that this argument is a
non-starter if we want to make the WAL receiver a maximum available.

>> That'd still switch to a different method, something we do not want...
> 
> Ok, do not want means we do not want. Will try change behavior.

Thanks Sergei for considering it.  The code paths touched are
sensitive, so we had better be careful here.
--
Michael