Re: Support for N synchronous standby servers - take 2

Hi,

On 2015-06-26 AM 12:49, Sawada Masahiko wrote:
> On Thu, Jun 25, 2015 at 7:32 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>>
>> 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.
>>
>
> I'm not sure specific implementation yet, but I came up with solution
> for this case.
>
> For example,
> - s_s_name = '1(a, b), c, d'
> The priority of both 'a' and 'b' are 1, and 'c' is 2, 'd' is 3.
> i.g, 'b' and 'c' are potential sync node, and the quorum commit is
> enable only between 'a' and 'b'.
>
> - s_s_name = 'a, 1(b,c), d'
> priority of 'a' is 1, 'b' and 'c' are 2, 'd' is 3.
> So the quorum commit with 'b' and 'c' will be enabled after 'a' down.
>

Do we really need to add a number like '1' in '1(a, b), c, d'?

The order of writing names already implies priorities like 2 & 3 for c & d,
respectively, like in your example. Having to write '1' for the group '(a, b)'
seems unnecessary, IMHO. Sorry if I have missed any previous discussion where
its necessity was discussed.

So, the order of writing standby names in the list should declare their
relative priorities and parentheses (possibly nested) should help inform about
the grouping (for quorum?)

Thanks,
Amit