What sort algorithm provides the best worst-case performance?

Question

What is the fastest known sort algorithm for absolute worst case? I don\'t care about best case and am assuming a gigantic data set if that even matters.

Answer 1

If you are using binary comparisons, the best possible sort algorithm takes O(N log N) comparisons to complete. If you're looking for something with good worst case performance, I'd look at MergeSort and HeapSort since they are O(N log N) algorithms in all cases.

HeapSort is nice if all your data fits in memory, while MergeSort allows you to do on-disk sorts better (but takes more space overall).

There are other less-well-known algorithms mentioned on the Wikipedia sorting algorithm page that all have O(n log n) worst case performance. (based on comment from mmyers)