Re: Parallel query execution

On Wed, Jan 16, 2013 at 01:37:28PM +0900, Michael Paquier wrote:
>
>
> On Wed, Jan 16, 2013 at 1:32 PM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> On Wed, Jan 16, 2013 at 01:28:18PM +0900, Michael Paquier wrote:
> >
> >
> > On Wed, Jan 16, 2013 at 1:22 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> >
> > Claudio, Stephen,
> >
> > It really seems like the areas where we could get the most "bang for
> the
> > buck" in parallelism would be:
> >
> > 1. Parallel sort
> > 2. Parallel aggregation (for commutative aggregates)
> > 3. Parallel nested loop join (especially for expression joins, like
> GIS)
> >
> > parallel data load? :/
>
> We have that in pg_restore, and I think we are getting parallel dump in
> 9.3, right? Unfortunately, I don't see it in the last 9.3 commit-fest.
> Is it still being worked on?
>
> Not exactly, I meant something like being able to use parallel processing when
> doing INSERT or COPY directly in core. If there is a parallel processing
> infrastructure, it could also be used for such write operations. I agree that
> the cases mentioned by Josh are far more appealing though...

I am not sure how a COPY could be easily parallelized, but I supposed it
could be done as part of the 1GB segment feature. People have
complained that COPY is CPU-bound, so it might be very interesting to
see if we could offload some of that parsing overhead to a child.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +