On 08/30/2016 05:35 PM, Michael Paquier wrote:
> On Wed, Aug 31, 2016 at 7:32 AM, Bruce Momjian <bruce@momjian.us> wrote:
>> On Tue, Aug 30, 2016 at 03:22:18PM -0700, Josh Berkus wrote:
>>> 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?
>>
>> As I understand it, it can continue with those three servers sending a
>> confirmation back.
>
> Assuming that all servers are connected at the moment decision is
> made, you need to wait for s1, s2 *and* s3 to acknowledge depending on
> synchronous_commit. By default that would be waiting for the LSN to
> have been flushed on all of them. And the important point to get is
> that what has been committed is dependent on the order of the items
> listed. This is not quorum commit, in which case having only
> confirmation from 3 servers in the set of 5 servers listed would be
> fine.
>
> If for example s2 and s4 are not connected at the moment of the
> decision, you'd need to wait for acknowledgment from s1, s3 and s5
> before moving on.
OK, so this says to me that we need a bunch of additional documentation
on this feature, because the existing docs read like it's "any 3 out of
the list" instead of "the first 3 which are connected".
--
--
Josh Berkus
Red Hat OSAS
(any opinions are my own)