Re: Separation walsender & normal backends

On 25/04/17 17:13, Fujii Masao wrote:
> On Tue, Apr 25, 2017 at 11:34 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Andres Freund <andres(at)anarazel(dot)de> writes:
>>> I've for a while suspected that the separation & duplication of
>>> infrastructure between walsenders and normal backends isn't nice.
>>
>> I think we should consider a more radical solution: trying to put
>> general SQL query capability into the replication protocol was a
>> bad idea and we should revert it while we still can. The uglinesses
>> you mention aren't merely implementation issues, they're an indication
>> that that concept is broken in itself.
>
> I think that it's worth considering this option in order to "stabilize"
> logical replication stuff before the release. The table sync patch
> (which allows walsender to run normal queries) introduced such
> uglinesses and increased the complexity in logical rep code.
> OTOH, I believe that logical replication is still useful even without
> initial table sync feature. So reverting the table sync patch seems
> possible idea.
>

I don't think that's good idea, the usefulness if much lower without the
initial copy. The original patch for this added new commands to
replication protocol, adding generic SQL interface was result of request
in the reviews.

I personally don't mind moving back my original idea of special commands
if that was the consensus, but previous consensus was to do SQL instead.

--
Petr Jelinek http://www.2ndQuadrant.com/
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