On 08/30/2016 06:32 PM, Amit Langote wrote:
> 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.
??? It's always been possible for me to give multiple standbys the same
name, making a de-facto group.
--
--
Josh Berkus
Red Hat OSAS
(any opinions are my own)
