Re: Append with naive multiplexing of FDWs

On Thu, Dec 5, 2019 at 1:12 PM Bruce Momjian <bruce@momjian.us> wrote:
> I agree with Stephen's request.  We have been waiting for the executor
> rewrite for a while, so let's just do something simple and see how it
> performs.

I'm sympathetic to the frustration here, and I think it would be great
if we could find a way forward that doesn't involve waiting for a full
rewrite of the executor.  However, I seem to remember that when we
tested the various patches that various people had written for this
feature (I wrote one, too) they all had a noticeable performance
penalty in the case of a plain old Append that involved no FDWs and
nothing asynchronous. I don't think it's OK to have, say, a 2%
regression on every query that involves an Append, because especially
now that we have partitioning, that's a lot of queries.

I don't know whether this patch has that kind of problem. If it
doesn't, I would consider that a promising sign.

-- 
Robert Haas
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