Re: Change pg_last_xlog_receive_location not to move backwards

On Tue, Jan 25, 2011 at 4:25 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Thu, Jan 13, 2011 at 2:40 AM, Fujii Masao <masao.fujii@gmail.com> wrote:
>> On Thu, Jan 13, 2011 at 4:24 PM, Fujii Masao <masao.fujii@gmail.com> wrote:
>>> So I'm thinking to change pg_last_xlog_receive_location not to
>>> move backwards.
>>
>> The attached patch does that.
>
> It looks to me like this is changing more than just the return value
> of pg_last_xlog_receive_location.  receivedUpto isn't only used for
> that one function, and there's no explanation in your email or in the
> patch of why the new behavior is correct and/or better for the other
> places where it's used.
>
> This email from Heikki seems to indicate that there's a reason for the
> current behavior:
>
> http://archives.postgresql.org/pgsql-hackers/2010-06/msg00586.php

Yes, so I didn't change that behavior, i.e., even with the patch, SR still
always starts from the head of the WAL segment, not the middle of that.
What I changed is only the return value of pg_last_xlog_receive_location.
Am I missing something?

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center