Re: Proposal: speeding up GIN build with parallel workers

On Fri, Jan 15, 2016 at 5:38 PM, Constantin S. Pan <kvapen(at)gmail(dot)com> wrote:
> In current state the implementation is just a proof of concept
> and it has all the configuration hardcoded, but it already works as is,
> though it does not speed up the build process more than 4 times on my
> configuration (12 CPUs). There is also a problem with temporary tables,
> for which the parallel mode does not work.

I have yet to see a case where parallel query, with any current or
pending patch, gets more than about a 4x speedup. I can't think of
any reason that there should be a wall at 4x, and I'm not sure we're
hitting the wall there for the same reason in all cases. But your
observation corresponds to my experience.

I hope we eventually figure out how to make that much better, but I
wouldn't feel too bad about being at that spot now. 4x faster is
still a lot faster.

--
Robert Haas
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