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Message-ID: <4C7C05B2.7030207@gmail.com>
Date: Mon, 30 Aug 2010 21:25:38 +0200
From: Yeb Havinga <yebhavinga@gmail.com>
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To: Greg Smith <greg@2ndquadrant.com>
CC: Eliot Gable <egable+pgsql-performance@gmail.com>,
	pgsql-performance@postgresql.org
Subject: Re: GPU Accelerated Sorting
References: <AANLkTimjYxrvMGMLhh3q=82iNiKKjQvPRcrsgX7DHcMp@mail.gmail.com>
	<4C7BBAA1.6040808@2ndquadrant.com>
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Greg Smith wrote:
> This comes up every year or so.  The ability of GPU offloading to help 
> with sorting has to overcome the additional latency that comes from 
> copying everything over to it and then getting all the results back.  
> If you look at the typical types of sorting people see in PostgreSQL, 
> it's hard to find ones that are a) big enough to benefit from being 
> offloaded to the GPU like that, while also being b) not so 
> bottlenecked on disk I/O that speeding up the CPU part matters.  And 
> if you need to sort something in that category, you probably just put 
> an index on it instead and call it a day.
>
> If you made me make a list of things I'd think would be worthwhile to 
> spend effort improving in PostgreSQL, this would be on the research 
> list, but unlikely to even make my personal top 100 things that are 
> work fiddling with.
Related is 'Parallelizing query optimization' 
(http://www.vldb.org/pvldb/1/1453882.pdf) in which they actually 
experiment with PostgreSQL. Note that their target platform is general 
purpose CPU, not a SIMD GPU processor.

-- Yeb