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Re: Parallel query execution

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: Parallel query execution
Date: 2013-01-16 17:11:42
Message-ID: 20130116171142.GA1099@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
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. +


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