Re: Support for N synchronous standby servers - take 2

On Sun, Jan 31, 2016 at 5:18 PM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> On Sun, Jan 31, 2016 at 5:08 PM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>> On Sun, Jan 31, 2016 at 1:17 PM, Michael Paquier
>> <michael.paquier@gmail.com> wrote:
>>> On Thu, Jan 28, 2016 at 10:10 PM, Masahiko Sawada wrote:
>>>> By the discussions so far, I'm planning to have several replication
>>>> methods such as 'quorum', 'complex' in the feature, and the each
>>>> replication method specifies the syntax of s_s_names.
>>>> It means that s_s_names could have the number of sync standbys like
>>>> what current patch does.
>>>
>>> What if the application_name of a standby node has the format of an integer?
>>
>> Even if the standby has an integer as application_name, we can set
>> s_s_names like '2,1,2,3'.
>> The leading '2' is always handled as the number of sync standbys when
>> s_r_method = 'priority'.
>
> Hm. I agree with Fujii-san here, having the number of sync standbys
> defined in a parameter that should have a list of names is a bit
> confusing. I'd rather have a separate GUC, which brings us back to one
> of the first patches that I came up with, and a couple of people,
> including Josh were not happy with that because this did not support
> real quorum. Perhaps the final answer would be really to get a set of
> hooks, and a contrib module making use of that.

Yeah, I agree with having set of hooks, and postgres core has simple
multi sync replication mechanism like you suggested at first version.

Regards,

--
Masahiko Sawada