On Thu, Oct 29, 2015 at 11:16 PM, Fujii Masao <masao.fu...@gmail.com> wrote: > On Thu, Oct 22, 2015 at 12:47 AM, Masahiko Sawada <sawada.m...@gmail.com> > wrote: >> On Tue, Oct 20, 2015 at 8:10 PM, Beena Emerson <memissemer...@gmail.com> >> wrote: >>> >>> On Mon, Oct 19, 2015 at 8:47 PM, Masahiko Sawada <sawada.m...@gmail.com> >>> wrote: >>>> >>>> >>>> Hi, >>>> >>>> Attached patch is a rough patch which supports multi sync replication >>>> by another approach I sent before. >>>> >>>> The new GUC parameters are: >>>> * synchronous_standby_num, which specifies the number of standby >>>> servers using sync rep. (default is 0) >>>> * synchronous_replication_method, which specifies replication method; >>>> priority or quorum. (default is priority) >>>> >>>> The behaviour of 'priority' and 'quorum' are same as what we've been >>>> discussing. >>>> But I write overview of these here again here. >>>> >>>> [Priority Method] >>>> The standby server has each different priority, and the active standby >>>> servers having the top N priroity are become sync standby server. >>>> If synchronous_standby_names = '*', the all active standby server >>>> would be sync standby server. >>>> If you want to set up standby like 9.5 or before, you can set >>>> synchronous_standby_num = 1. >>>> >>> >>> >>> I used the following setting with 2 servers A and D connected: >>> >>> synchronous_standby_names = 'A,B,C,D' >>> synchronous_standby_num = 2 >>> synchronous_replication_method = 'priority' >>> >>> Though s_r_m = 'quorum' worked fine, changing it to 'priority' caused >>> segmentation fault. >>> >> >> Thank you for taking a look! >> This patch is a tool for discussion, so I'm not going to fix this bug >> until getting consensus. >> >> We are still under the discussion to find solution that can get consensus. >> I felt that it's difficult to select from the two approaches within >> this development cycle, and there would not be time to implement such >> big feature even if we selected. >> But this feature is obviously needed by many users. >> So I'm considering more simple and extensible something solution, the >> idea I posted is one of them. >> The another worth considering approach is that just specifying the >> number of sync standby. It also can cover the main use cases in >> some-cases. > > Yes, it covers main and simple use case like "I want to have multiple > synchronous replicas!". Even if we miss quorum commit at the first > version, the feature is still very useful.
It can cover not only the case you mentioned but also main use case Michael mentioned by setting same application_name. And that first version patch is almost implemented, so just needs to be reviewed. I think that it would be good to implement the simple feature at the first version, and then coordinate the design based on opinion and feed backs from more user, use-case. Regards, -- Masahiko Sawada -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
