Re: patch proposal

On Thu, Aug 18, 2016 at 3:37 PM, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
wrote:

> On Tue, Aug 16, 2016 at 11:06 PM, Stephen Frost <sfrost(at)snowman(dot)net>
> wrote:
> > I could see supporting an additional "pause" option that means "pause at
> > the end of WAL if you don't reach the recovery target point". I'd also
> > be happy with a warning being emitted in the log if the recovery target
> > point isn't reached before reaching the end of WAL, but I don't think it
> > makes sense to change the existing behavior.
>
> Indeed, let's not change the existing behavior. A warning showing up
> by default would be useful in itself, even if there are people that I
> think set up overly high recovery targets to be sure to replay WAL as
> much as possible. As recovery_target_action has meaning when a
> recovery target has been reached, I would guess that we would want a
> new option that has the same mapping value as recovery_target_action,
> except that it activates when the target recovery is *not* reached.
> Hence it would be possible to shutdown, pause or promote at will when
> recovery completes, and be able to take a separate action is the
> recovery target is indeed reached. The default of this parameter would
> be "promote", which is what happens now.
>

Yes, a new parameter with same options as recovery_target_action is the
idea i had in mind as well and i have the following queries while working
through the patch design -

*Query 1*

What about the existing parameter called "recovery_target" which accepts
only one value "immediate", which will be similar to the "promote" option
with the to-be-introduced new parameter.
Since this parameter's behaviour will be incorporated into the new
parameter, I think, this parameter can be deprecated from the next
PostgreSQL version ?

*Query 2*

I am thinking that the new parameter name should be
"recovery_target_incomplete" or "recovery_target_incomplete_action" which
(by name) suggests that recovery target point is not yet reached and
accepts options "pause","promote" and "shutdown".

The other alternative name i thought of was -
"recovery_target_immediate_action", which (by name) suggests the action to
be taken when the recovery does not reach the actual set recovery target
and reaches immediate consistent point.

Any comments, suggestions ?

Regards,
Venkata B N

Fujitsu Australia