From: | Josh Berkus <josh(at)agliodbs(dot)com> |
---|---|
To: | Bruce Momjian <bruce(at)momjian(dot)us> |
Cc: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, pgsql-advocacy(at)postgresql(dot)org |
Subject: | Re: DRAFT 9.6 release |
Date: | 2016-08-30 22:22:18 |
Message-ID: | 31a9471d-80b1-fd76-0e1e-82d0840aedcc@agliodbs.com |
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Lists: | pgsql-advocacy |
On 08/30/2016 02:28 PM, Bruce Momjian wrote:
> On Tue, Aug 30, 2016 at 09:41:59AM -0700, Josh Berkus wrote:
>> On 08/29/2016 06:24 PM, Amit Langote wrote:
>>> On 2016/08/30 8:00, Josh Berkus wrote:
>>>> Folks,
>>>>
>>>> Here is a preliminary draft of a 9.6 release announcement.
>>>>
>>>> Please comment, suggest, edit, make comments on the wiki, whatever.
>>>>
>>>> https://wiki.postgresql.org/wiki/96releasedraft
>>>
>>> In the section on scale out, I see quorum commit mentioned but it's not
>>> part of what's offered in 9.6. The quorum part is still being worked on:
>>> https://commitfest.postgresql.org/10/696/
>>
>> Oh, figures the one feature I haven't tested would be the one which
>> isn't right. So what DID get added to 9.6? Is it still a significant
>> feature?
>
> We did this (from the 9.6 release notes):
>
> Allow synchronous replication to support multiple simultaneous
> synchronous standby servers, not just one (Masahiko Sawada,
> Beena Emerson, Michael Paquier, Fujii Masao, Kyotaro Horiguchi)
>
> The number of standby servers that must acknowledge a commit
> before it is considered complete is now configurable as part of
> the synchronous_standby_names parameter.
>
> You can see the details here, e.g. "3 (s1, s2, s3, s4)"
>
> https://www.postgresql.org/docs/9.6/static/runtime-config-replication.html#GUC-SYNCHRONOUS-STANDBY-NAMES
So that's usually what I mean when I say quorum commit. But apparently
our feature does something slightly different?
"For example, a setting of 3 (s1, s2, s3, s4) makes transaction commits
wait until their WAL records are received by three higher-priority
standbys chosen from standby servers s1, s2, s3 and s4"
What does that mean exactly? If I do:
3 ( s1, s2, s3, s4, s5 )
And a commit is ack'd by s2, s3, and s5, what happens?
--
--
Josh Berkus
Red Hat OSAS
(any opinions are my own)
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