On 2016/08/31 10:25, Josh Berkus wrote:
> On 08/30/2016 06:20 PM, Josh Berkus wrote:
>> On 08/30/2016 06:12 PM, Michael Paquier wrote:
>>
>>> Really? Here are the doc quotes that I guess matter, and I read that
>>> differently than you do:
>>> If any of the current synchronous standbys disconnects for whatever
>>> reason, it will be replaced immediately with the next-highest-priority
>>> standby.
>>> [...]
>>> 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.
>>>
>>> This clearly says that we wait for the servers that have a higher
>>> priority, meaning that we do *not* wait for any k elements in a set of
>>> n listed, but suggest that the order of the element matters.
>>
>> Yeah, the problem is that "higher priority" isn't defined, and could
>> mean a lot of things. It *is* defined in the actual section on
>> synchronous standby, though (25.2.8.2.); maybe what we need is less docs
>> under the GUC and more references to that?
>>
>> Otherwise, you're going to have lots of people confused that it's
>> actually quorum commit, as witnessed by the current discussion. Right
>> now what's in the GUC doc page appears to be complete but isn't.
>
> Also, if I do this:
>
>
> 2 ( g1, g2, g3 )
>
> ... and g1, g2 and g3 are *groups* of three standbys each, what happens?
> Does it wait for one or more responses from g1 and from g2, or does
> getting two responses from g1 trigger a commit?
We do not support specifying groups either. Names refer to the actual
standby names. Groups part of the earlier proposal(s) was taken out of
the patch, IIRC.
Thanks,
Amit