Re: Quorum commit for multiple synchronous replication.

Fujii Masao <masao.fujii@gmail.com>

From: Fujii Masao <masao.fujii@gmail.com>
To: Michael Paquier <michael.paquier@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, Amit Kapila <amit.kapila16@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Petr Jelinek <petr@2ndquadrant.com>, Vik Fearing <vik@2ndquadrant.fr>, Simon Riggs <simon@2ndquadrant.com>, Josh Berkus <josh@agliodbs.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2016-12-16T08:04:50Z
Lists: pgsql-hackers
On Fri, Dec 16, 2016 at 2:38 PM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> On Thu, Dec 15, 2016 at 6:08 PM, Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>> Attached latest v12 patch.
>> I changed behavior of "N (standby_list)" to use the priority method
>> and incorporated some review comments so far. Please review it.
>
> Some comments...
>
> +    Another example of <varname>synchronous_standby_names</> for multiple
> +    synchronous standby is:
> Here standby takes an 's'.
>
> +    candidates. The master server will wait for at least 2 replies from them.
> +    <literal>s4</> is an asynchronous standby since its name is not in the list.
> +   </para>
> "will wait for replies from at least two of them".
>
> + * next-highest-priority standby. In quorum method, the all standbys
> + * appearing in the list are considered as a candidate for quorum commit.
> "the all" is incorrect. I think you mean "all the" instead.
>
> + * NIL if no sync standby is connected. In quorum method, all standby
> + * priorities are same, that is 1. So this function returns the list of
> This is not true. Standys have a priority number assigned. Though it does
> not matter much for quorum groups, it gives an indication of their position
> in the defined list.
>
>  #synchronous_standby_names = ''    # standby servers that provide sync rep
>  -               # number of sync standbys and comma-separated list of application_name
>  +               # synchronization method, number of sync standbys
>  +               # and comma-separated list of application_name
>                  # from standby(s); '*' = all
> The formulation is funny here: "sync rep synchronization method".
>
> I think that Fujii-san has also some doc changes in his box. For anybody
> picking up this patch next, it would be good to incorporate the things
> I have noticed here.

Yes, I will. Thanks!

Regards,

-- 
Fujii Masao


Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →
  1. Set the priorities of all quorum synchronous standbys to 1.

  2. Improve documentation and comment for quorum-based sync replication.