On Sat, Oct 1, 2022 at 12:14 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I spent some time today looking into the question of what our qsort
> code actually does. I wrote a quick-n-dirty little test module
> (attached) to measure the number of comparisons qsort really uses
> for assorted sample inputs.
Reminds me of the other sort testing program that you wrote when the
B&M code first went in:
https://www.postgresql.org/message-id/18732.1142967137@sss.pgh.pa.us
This was notable for recreating the tests from the original B&M paper.
The paper uses various types of test inputs with characteristics that
were challenging to the implementation and worth specifically getting
right. For example, "saw tooth" input.
--
Peter Geoghegan