Re: Using quicksort for every external sort run

On Thu, Apr 7, 2016 at 11:10 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> I prefer units of tuples, with the GUC itself therefore being
> unitless. I suggest we call the parameter replacement_sort_threshold
> and document that (1) the ideal value may depend on the amount of CPU
> cache available to running processes, with more cache implying higher
> values; and (2) the ideal value may depend somewhat on the input data,
> with more correlation implying higher values. And then pick some
> value that you think is likely to work well for most people and call
> it good.

I really don't want to bikeshed about this, but I must ask: if the
name of the GUC must include the word "threshold", shouldn't it be
called quicksort_threshold?

My dictionary defines threshold as "any place or point of entering or
beginning". But this GUC does not govern where replacement selection
begins; it governs where it ends.

How do you feel about replacement_sort_tuples? We already use the word
"tuple" in the names of GUCs.

--
Peter Geoghegan