[GitHub] [incubator-pinot] wuwenw commented on pull request #6875: Potential Optmization for GroupBy Sorting Phase

[GitBox <gi...@apache.org>]

wuwenw commented on pull request #6875:
URL: https://github.com/apache/incubator-pinot/pull/6875#issuecomment-832356902


   > Is this same as standard order statistics algorithm which gives worst case linear time (compared to heap sort approach) for selecting k largest or smallest elements?
   
   The selection algorithm used here is [quickselct](https://en.wikipedia.org/wiki/Quickselect#Time_complexity), a partial quicksort algorithm. The best case and average performance is O(n) but the worst case is O(n^2). 


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