Re: parallel quicksort

Hi,

On 08/09/2010 12:04 AM, Mark Wong wrote:
> I've been playing around with a process based parallel quicksort
> (http://github.com/markwkm/quicksort) and I tried to shoehorn it into
> postgres because I wanted to see if I could sort more than integers.
> I've attached a patch that creates a new GUC to control the degree of
> parallelism and only modified the quicksort algorithm in quicksort.c.
> Trying to 'make install' quickly shows me the patch breaks zic and
> Andrew Gierth further pointed out on irc (a couple months back now)
> that user defined comparison functions won't work as expected in the
> forked processes (if I remember that correctly).

I'm not sure what the problems are, but the background worker
infrastructure I recently posted could possibly solve this problem, as
those are more like normal backends. (Assuming you were forking from the
backend).

> Hoping this could be useful, I wanted to put out what I had so far and
> see how far away this is from something workable. Not to mention that
> there are probably some improvements that could be make to the
> parallel quicksort algorithm.

Thanks for sharing.

Regards

Markus Wanner