On 25 June 2015 at 05:01, Michael Paquier <michael.paqu...@gmail.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/> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
