Re: Proposal : Parallel Merge Join

On Sat, Dec 10, 2016 at 7:59 AM, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> I would like to propose a patch for parallelizing merge join path.
> This idea is derived by analyzing TPCH results.
>
> I have done this analysis along with my colleagues Rafia sabih and Amit kaplia.
>
> Currently we already have infrastructure for executing parallel join,
> so we don't need any change at executor level. Only in path
> generation, we need to add partial paths for merge join, like we do
> for nest loop and hash join.

Hmm, so it seems my initial guess that we didn't need to bother
generating such paths was wrong. Oops.

This patch is hard to read because it is reorganizing a bunch of code
as well as adding new functionality. Perhaps you could separate it
into two patches, one with the refactoring and then the other with the
new functionality. Actually, though, I don't understand why you need
so much rearrangement....

--
Robert Haas
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