[GitHub] [flink] sunjincheng121 commented on a change in pull request #8359: [FLINK-11051][table] Add streaming window FlatAggregate to Table API

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sunjincheng121 commented on a change in pull request #8359: [FLINK-11051][table] Add streaming window FlatAggregate to Table API
URL: https://github.com/apache/flink/pull/8359#discussion_r282715615
 
 

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 File path: flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/WindowGroupedTable.java
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 @@ -54,4 +54,39 @@
 	 * </pre>
 	 */
 	Table select(Expression... fields);
+
+	/**
+	 * Performs a flatAggregate operation on a window grouped table. FlatAggregate takes a
+	 * TableAggregateFunction which returns multiple rows. Use a selection after flatAggregate.
+	 *
+	 * <p>Example:
+	 *
+	 * <pre>
+	 * {@code
+	 *   TableAggregateFunction tableAggFunc = new MyTableAggregateFunction
+	 *   tableEnv.registerFunction("tableAggFunc", tableAggFunc);
+	 *   windowGroupedTable
+	 *     .flatAggregate("tableAggFunc(a, b) as (x, y, z)")
+	 *     .select("key, window.start, x, y, z")
+	 * }
+	 * </pre>
+	 */
+	FlatAggregateTable flatAggregate(String tableAggregateFunction);
 
 Review comment:
   
   We should add the JavaDoc for `WindowGroupedTable` in `FlatAggregateTable`. e.g.:
   A table that performs flatAggregate on a {@link Table}, a {@link GroupedTable} or a {@link WndowGroupedTable}. 

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