[GitHub] [spark] HeartSaVioR commented on a change in pull request #29256: [SPARK-32456][SS] Check the Distinct by assuming it as Aggregate for Structured Streaming

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

HeartSaVioR commented on a change in pull request #29256:
URL: https://github.com/apache/spark/pull/29256#discussion_r463490810



##########
File path: sql/core/src/test/scala/org/apache/spark/sql/streaming/StreamingQuerySuite.scala
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@@ -1106,6 +1107,54 @@ class StreamingQuerySuite extends StreamTest with BeforeAndAfter with Logging wi
     }
   }
 
+  test("union in streaming query of append mode without watermark") {
+    val inputData1 = MemoryStream[Int]
+    val inputData2 = MemoryStream[Int]
+    withTempView("s1", "s2") {
+      inputData1.toDF().createOrReplaceTempView("s1")
+      inputData2.toDF().createOrReplaceTempView("s2")
+      val unioned = spark.sql(
+        "select s1.value from s1 union select s2.value from s2")
+      checkExceptionMessage(unioned)
+    }
+  }
+
+  test("distinct in streaming query of append mode without watermark") {
+    val inputData = MemoryStream[Int]
+    withTempView("deduptest") {
+      inputData.toDF().toDF("value").createOrReplaceTempView("deduptest")
+      val distinct = spark.sql("select distinct value from deduptest")
+      checkExceptionMessage(distinct)
+    }
+  }
+
+  test("distinct in streaming query of complete mode") {
+    val inputData = MemoryStream[Int]
+    withTempView("deduptest") {
+      inputData.toDF().toDF("value").createOrReplaceTempView("deduptest")
+      val distinct = spark.sql("select distinct value from deduptest")
+
+      testStream(distinct, Complete)(
+        AddData(inputData, 1, 2, 3, 3, 4),
+        CheckAnswer(Row(1), Row(2), Row(3), Row(4))

Review comment:
       The behavior is a bit confusing to me actually. What result would we expect if there's another batch `(3, 3, 4, 5)`? 
   (I'm not asking which values Spark are providing. I'm asking which values are "reasonable" and "clear".)




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