Re: Using quicksort for every external sort run - Mailing list pgsql-hackers

Hm. Here is a log-log chart of those results (sorry for html mail). I'm not really sure if log-log is the right tool to use for a O(nlog(n)) curve though. 

I think the take-away is that this is outside the domain where any interesting break points occur. Maybe run more tests on the low end to find where the tapesort can generate a single tape and avoid the merge and see where the discontinuity is with quicksort for the various work_mem sizes. 

And can you calculate an estimate where the domain would be where multiple passes would be needed for this table at these work_mem sizes? Is it feasible to test around there?