wForget commented on PR #1428:
URL: 
https://github.com/apache/datafusion-comet/pull/1428#issuecomment-2684022663

   Integral divide of `decimal` type has inconsistent behavior.
   
    test:
   
   ```
     test("test integral divide") {
       withTable("t1", "t2") {
         if (isSpark34Plus) {
           // Decimal support requires Spark 3.4 or later
           sql("create table t2(c1 DECIMAL(38, 37), c2 DECIMAL(38, 37)) using 
parquet")
           sql("insert into t2 values(6.0096743305738933273387748827369321010, 
6.0096763826458053191384497987259478584)")
           checkSparkAnswerAndOperator("select c1 / c2, cast((c1 / c2 ) as 
long), c1 div c2 from t2 order by c1")
         }
       }
     }
   ```
   
   Results do not match:
   
   ```
   == Results ==
   !== Correct Answer - 1 ==                                                    
          == Spark Answer - 1 ==
    struct<(c1 / c2):decimal(38,6),CAST((c1 / c2) AS BIGINT):bigint,(c1 div 
c2):bigint>   struct<(c1 / c2):decimal(38,6),CAST((c1 / c2) AS 
BIGINT):bigint,(c1 div c2):bigint>
   ![1.000000,1,0]                                                              
          [1.000000,1,1]
   ```
   
   This is due to the rounding behavior of `decimal_div`:
   
https://github.com/apache/datafusion-comet/blob/58a36b62004c1e300d7f3113d9a64713a94c0db9/native/spark-expr/src/math_funcs/div.rs#L72-L76
   


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