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.
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
