On 25 November 2015 at 00:33, Peter Geoghegan <pg@heroku.com> wrote:
Parallel sort is very important. Robert, Amit and I had a call about this earlier today. We're all in agreement that this should be extended in that direction, and have a rough idea about how it ought to fit together with the parallelism primitives. Parallel sort in 9.6 could certainly happen -- that's what I'm aiming for. I haven't really done preliminary research yet; I'll know more in a little while.
Glad to hear it, I was hoping to see that.
> How about we commit it with a sort_algorithm = 'foo' parameter so we can > compare things before release of 9.6?
I had a debug GUC (like the existing one to disable top-N heapsorts) that disabled "quicksort with spillover". That's almost the opposite of what you're asking for, though, because that makes us never use a heap. You're asking for me to write a GUC to always use a heap.
I'm asking for a parameter to confirm results from various algorithms, so we can get many eyeballs to confirm your work across its breadth. This is similar to the original trace_sort parameter which we used to confirm earlier sort improvements. I trust it will show this is good and can be removed prior to release of 9.6.
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
