On Sep 3, 2016, at 1:39 AM, Bruce Momjian <bruce@momjian.us> wrote:
>> On Fri, Sep 2, 2016 at 07:50:58AM +0530, Robert Haas wrote:
>> But if you have BOTH features, then you can set
>> synchronous_standby_names to require an ACK from *every* standby, and
>> you can set synchronous_commit=remote_apply so that you wait for WAL
>> to be applied, not just fsync'd, and now you are guaranteed that
>> whenever you make a change on the master and then read it back from
>> any one of your read-replicas, it will be there! And that, IMHO, is
>> pretty cool.
>
> Are we clear on how useful this will be because of the delay in applying
> WAL, particularly for when conflicting read-only queries are running?
Not entirely, but people are already doing read-scaling with replicas, so having an option to make that reliable seems
likea good thing.
...Robert