Re: INSERT ... ON CONFLICT UPDATE and logical decoding

On Fri, Feb 20, 2015 at 3:52 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> On 2015-02-20 15:44:12 -0800, Peter Geoghegan wrote:
>> On Thu, Feb 19, 2015 at 2:11 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>> > Yes. It'd be easiest if the only the final insert/update were actually
>> > WAL logged as full actions.
>>
>> Well, that implies that we'd actually know that we'd succeed when WAL
>> logging the speculative heap tuple's insertion.
>
> I don't think it does. It'd certainly be possible to simply only emit
> the final WAL logging action once the insertion has actually
> non-speculatively succeeded. We might decide against that for
> eefficiency or complexity reasons, but it'd be far from impossible or
> even ugly. We could even not log the actual values for the speculative
> insertion - after all, those aren't needed if we crash halfway
> through...

I think that that would be prohibitively complex and inefficient,
though. No? I will concede that it's probably possible in principle,
but that seems like a pretty academic point.

--
Peter Geoghegan