Re: GPU Accelerated Sorting

On a similar note, is Postgres' Quicksort a dual-pivot quicksort? This can be up to 2x as fast as a normal quicksort (25% fewer swap operations, and swap operations are more expensive than compares for most sorts).

Just google 'dual pivot quicksort' for more info.

And before anyone asks -- two pivots (3 partitions) is optimal. See http://mail.openjdk.java.net/pipermail/core-libs-dev/2009-September/002676.html

On Aug 30, 2010, at 12:25 PM, Yeb Havinga wrote:

> 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
>
>
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