On Thu, Aug 21, 2014 at 2:54 PM, <furuyao@pm.nttdata.co.jp> wrote:
>> When replication slot is not specified in pg_receivexlog, the flush
>> location in the feedback message always indicates invalid. So there seems
>> to be no need to send the feedback as soon as fsync is issued, in that
>> case.
>> How should this option work when replication slot is not specified?
>
> Thanks for the review!
>
> The present is not checking the existence of specification of -S.
>
> The use case when replication slot is not specified.
>
> Because it does fsync, it isn't an original intention.
> remote_write is set in synchronous_commit.
>
> To call attention to the user, append following documents.
> "If you want to report the flush position to the server, should use -S option."
>
Thank you for updating the patch.
I reviewed the patch.
First of all, I think that we should not append the above message to
section of '-r' option.
(Or these message might not be needed at all)
Whether flush location in feedback message is valid, is not depend on
'-r' option.
If we use '-r' option and 'S' option (i.g., replication slot) then
pg_receivexlog informs valid flush
location to primary server at the same time as doing fsync.
But, if we don't specify replication slot then the flush location in
feedback message always invalid.
So I think Fujii-san pointed out that sending of invalid flush
location is not needed
if pg_receivexlog does not use replication slot.
Regards,
-------
Sawada Masahiko
