On Tue, Nov 24, 2015 at 4:46 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> 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.
My patch updates trace_sort messages. trace_sort doesn't change the
behavior of anything. The only time we've ever done anything like this
was for Top-N heap sorts.
This is significantly more inconvenient than you think. See the
comments in the new dumpbatch() function.
--
Peter Geoghegan