Re: libpq changes for synchronous replication

On Mon, Dec 6, 2010 at 12:54 AM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
> On Mon, Dec 6, 2010 at 3:07 AM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
>> The one time this year top-posting seems appropriate...this patch seems
>> stalled waiting for some sort of response to the concerns Alvaro raised
>> here.
>
> Sorry for the delay. I didn't have the time.
>
>> I gave this a look.  It seems good, but I'm not sure about this bit:
>
> Thanks for the review!
>
>> I guess this was OK when this was conceived as CopyXlog, but since it's
>> now a generic mechanism, this seems a bit unwise.  Should this be
>> reconsidered so that it's possible to change the format or number of
>> columns?
>
> I changed CopyBothResponse message so that it includes the format
> and number of columns of copy data. Please see the attached patch.
>
>> (The paragraph added to the docs is also a bit too specific about this
>> being used exclusively in streaming replication, ISTM)
>
> Yes. But it seems difficult to generalize the docs more because currently
> only SR uses Copy-both. So I had to write that, for example, the condition
> to get into the state is only "START REPLICATION" command.
>
>> While modifying the code, it occurred to me that we might have to add new
>> ExecStatusType like PGRES_COPY_BOTH and use that for CopyBoth mode,
>> for the sake of consistency. But since it's just alias of PGRES_COPY_BOTH
>> for now, i.e., there is no specific behavior for that ExecStatusType, I
>> don't
>> think that it's worth adding that yet.
>>
>>
>> I'm not so sure about this.  If we think that it's worth adding a new
>> possible state, we should do so now; we will not be able to change this
>> behavior later.
>
> OK. I added that new state.

Committed with just a few changes to the documentation.

--
Robert Haas
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