[GitHub] [spark] HyukjinKwon commented on a change in pull request #29837: [SPARK-32463][DOCS] SQL data type compatibility

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HyukjinKwon commented on a change in pull request #29837:
URL: https://github.com/apache/spark/pull/29837#discussion_r492769769



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File path: docs/sql-ref-datatypes.md
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@@ -314,3 +314,33 @@ SELECT COUNT(*), c2 FROM test GROUP BY c2;
 |        3| Infinity|
 +---------+---------+
 ```
+
+#### Data type compatibility
+
+The following is the hierarchy of data type compatibility. In an operation involving different and compatible data types, these will be promoted to the lowest common top type to perform the operation.
+
+For example, if you have an add operation between an integer and a float, the integer will be treated as a float, the least common compatible type, resulting the operation in a float.
+
+The most common operations where this hierarchy is applied are:

Review comment:
       I believe we have much more complicated rules than here ..  see `TypeCoercion.scala`.




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