[jira] [Created] (KYLIN-6045) SUM Query Decimal Precision Anomaly

["Guoliang Sun (Jira)" <ji...@apache.org>]

Guoliang Sun created KYLIN-6045:
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             Summary: SUM Query Decimal Precision Anomaly
                 Key: KYLIN-6045
                 URL: https://issues.apache.org/jira/browse/KYLIN-6045
             Project: Kylin
          Issue Type: Bug
    Affects Versions: 5.0.0
            Reporter: Guoliang Sun


When generating the Spark plan for a query, a `cast` conversion is added for the `sum` aggregation in `AggregatePlan.buildAgg`. At this point, the input type is the column type, causing the precision of the `cast` to be reduced. This results in the query returning `null`.
h3. Example

- The column precision in the Hive table is `decimal(19,6)`.  
- The model measure precision is `decimal(29,6)`.  
- When querying, the result will be `null`.  

In the Spark event log for the query, the `cast` precision is `decimal(19,6)`. Directly retrieving data from the Parquet file yields the following:  
- When the `cast` precision is `DECIMAL(19,6)`, the result is `null`.  
- When the `cast` precision is `DECIMAL(29,6)`, the result is correct.



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