[GitHub] [spark] cloud-fan commented on a change in pull request #30212: [SPARK-33308][SQL] Refactor current grouping analytics

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

cloud-fan commented on a change in pull request #30212:
URL: https://github.com/apache/spark/pull/30212#discussion_r601143106



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File path: docs/sql-ref-syntax-qry-select-groupby.md
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@@ -42,6 +42,21 @@ aggregate_name ( [ DISTINCT ] expression [ , ... ] ) [ FILTER ( WHERE boolean_ex
 
 ### Parameters
 
+* **grouping_expression**
+
+    Specifies the criteria based on which the rows are grouped together. The grouping of rows is performed based on
+    result values of the grouping expressions. A grouping expression may be a column alias, a column position
+    or an expression.

Review comment:
       not relate to this PR, but we can give some examples to make it easy to understand.
   ```
   A grouping expression may be a column alias like `GROUP BY a`, a column position
   like `GROUP BY 0`, or an expression like `GROUP BY a + b`.
   ```




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