Re: Support for N synchronous standby servers - take 2

On 25 June 2015 at 05:01, Michael Paquier <michael(dot)paquier(at)gmail(dot)com> wrote:

> On Thu, Jun 25, 2015 at 12:57 PM, Fujii Masao wrote:
> > On Thu, Jun 25, 2015 at 12:15 PM, Michael Paquier wrote:
> >> and that's actually equivalent to that in
> >> the grammar: 1(AAA,BBB,CCC).
> >
> > I don't think that they are the same. In the case of 1(AAA,BBB,CCC),
> while
> > two servers AAA and BBB are running, the master server may return a
> success
> > of the transaction to the client just after it receives the ACK from BBB.
> > OTOH, in the case of AAA,BBB, that never happens. The master must wait
> for
> > the ACK from AAA to arrive before completing the transaction. And then,
> > if AAA goes down, BBB should become synchronous standby.
>
> Ah. Right. I missed your point, that's a bad day... We could have
> multiple separators to define group types then:
> - "()" where the order of acknowledgement does not matter
> - "[]" where it does not.
> You would find the old grammar with:
> 1[AAA,BBB,CCC]
>

Let's start with a complex, fully described use case then work out how to
specify what we want.

I'm nervous of "it would be good ifs" because we do a ton of work only to
find a design flaw.

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
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