sunjincheng121 commented on a change in pull request #7235: [FLINK-10976]
[table] Add support for aggregate to table API
URL: https://github.com/apache/flink/pull/7235#discussion_r244670679
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
##########
@@ -1080,6 +1114,47 @@ class GroupedTable(
val withResolvedAggFunctionCall = fieldExprs.map(replaceAggFunctionCall(_,
table.tableEnv))
select(withResolvedAggFunctionCall: _*)
}
+
+ /**
+ * Performs an aggregate operation with an aggregate function. Use this
before a selection
+ * to perform the selection operation. The output will be flattened if the
output type is a
+ * composite type.
+ *
+ * Example:
+ *
+ * {{{
+ * val aggFunc: AggregateFunction[_, _] = new MyAggregateFunction
+ * tableEnv.registerFunction("aggFunc", aggFunc);
+ * table.groupBy('key).aggregate("aggFunc(a, b) as (f0, f1,
f2)").select('key, 'f0, 'f1)
+ * }}}
+ */
+ def aggregate(aggregateFunction: Expression): AggregatedTable = {
+ unwrap(aggregateFunction, table.tableEnv) match {
+ case _: AggFunctionCall | _: Aggregation =>
+ case _ => throw new ValidationException("Only AggregateFunction can be
used in aggregate.")
+ }
+
+ new AggregatedTable(table, groupKeys, aggregateFunction)
+ }
+
+ /**
+ * Performs an aggregate operation with an aggregate function. Use this
before a selection
+ * to perform the selection operation. The output will be flattened if the
output type is a
+ * composite type.
+ *
+ * Example:
+ *
+ * {{{
+ * val aggFunc: AggregateFunction[_, _] = new MyAggregateFunction
Review comment:
Can not using AggregateFunction[_, _].
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