Re: [Patch] ALTER SYSTEM READ ONLY

On Thu, Jun 18, 2020 at 6:39 AM Simon Riggs <simon@2ndquadrant.com> wrote:
> That doesn't appear to be very graceful. Perhaps objections could be assuaged by having a smoother transition and
perhapsnot even a full barrier, initially.
 

Yeah, it's not ideal, though still better than what we have now. What
do you mean by "a smoother transition and perhaps not even a full
barrier"? I think if you want to switch the primary to another machine
and make the old primary into a standby, you really need to arrest WAL
writes completely. It would be better to make existing write
transactions ERROR rather than FATAL, but there are some very
difficult cases there, so I would like to leave that as a possible
later improvement.

-- 
Robert Haas
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