mzabaluev opened a new issue, #1318:
URL: https://github.com/apache/auron/issues/1318

   **Describe the bug**
   The optimized helper function for finding the common prefix length is 
incorrect.
   
   **To Reproduce**
   1. Add this test to 
[`sort_exec.rs`](https://github.com/apache/auron/blob/99496ab5e8ee550eee2ec89f6495c85036efeeb6/native-engine/datafusion-ext-plans/src/sort_exec.rs):
   
   ```rust
       #[test]
       fn has_common_prefix_len_been_optimized_into_bogusness() {
           let cpl = common_prefix_len(&[0; 8], &[0; 8]);
           assert_eq!(cpl, 8);
           let cpl = common_prefix_len(&[0; 4], &[0; 4]);
           assert_eq!(cpl, 4);
           let cpl = common_prefix_len(&[0; 2], &[0; 2]);
           assert_eq!(cpl, 2);
           let cpl = common_prefix_len(&[0; 1], &[0; 1]);
           assert_eq!(cpl, 1);
       }
   ```
   
   2. Run the test.
   
   **Proposed fix**
   Change the `< min_len` comparisons to `<= min_len`.
   
   Or just replace with a simple implementation and benchmark if the tweaky one 
really regresses perf, e.g.:
   
   ```rust
   fn common_prefix_len(a: &[u8], b: &[u8]) -> usize {
       std::iter::zip(a, b)
           .position(|(x, y)| x != y)
           .unwrap_or_else(|| min(a.len(), b.len()))
   }
   ```
   
   
   


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