[SPARK-8930] [SQL] Throw a AnalysisException with meaningful messages if DataFrame#explode takes a star in expressions

Author: Yijie Shen <henry.yijieshen@gmail.com>

Closes #8057 from yjshen/explode_star and squashes the following commits:

eae181d [Yijie Shen] change explaination message
54c9d11 [Yijie Shen] meaning message for * in explode

3 files changed, 21 insertions, 2 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
index 82158e61e3..a684dbc3af 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
@@ -408,7 +408,7 @@ class Analyzer(
     /**
      * Returns true if `exprs` contains a [[Star]].
      */
-    protected def containsStar(exprs: Seq[Expression]): Boolean =
+    def containsStar(exprs: Seq[Expression]): Boolean =
       exprs.exists(_.collect { case _: Star => true }.nonEmpty)
   }
 
@@ -602,6 +602,8 @@ class Analyzer(
    */
   object ResolveGenerate extends Rule[LogicalPlan] {
     def apply(plan: LogicalPlan): LogicalPlan = plan resolveOperators {
+      case g: Generate if ResolveReferences.containsStar(g.generator.children) =>
+        failAnalysis("Cannot explode *, explode can only be applied on a specific column.")
       case p: Generate if !p.child.resolved || !p.generator.resolved => p
       case g: Generate if !g.resolved =>
         g.copy(generatorOutput = makeGeneratorOutput(g.generator, g.generatorOutput.map(_.name)))
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisTest.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisTest.scala
index ee1f8f5425..53b3695a86 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisTest.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisTest.scala
@@ -71,6 +71,8 @@ trait AnalysisTest extends PlanTest {
     val e = intercept[Exception] {
       analyzer.checkAnalysis(analyzer.execute(inputPlan))
     }
-    expectedErrors.forall(e.getMessage.contains)
+    assert(expectedErrors.map(_.toLowerCase).forall(e.getMessage.toLowerCase.contains),
+      s"Expected to throw Exception contains: ${expectedErrors.mkString(", ")}, " +
+        s"actually we get ${e.getMessage}")
   }
 }
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
index 0212637a82..c49f256be5 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
@@ -134,6 +134,21 @@ class DataFrameSuite extends QueryTest with SQLTestUtils {
     )
   }
 
+  test("SPARK-8930: explode should fail with a meaningful message if it takes a star") {
+    val df = Seq(("1", "1,2"), ("2", "4"), ("3", "7,8,9")).toDF("prefix", "csv")
+    val e = intercept[AnalysisException] {
+      df.explode($"*") { case Row(prefix: String, csv: String) =>
+        csv.split(",").map(v => Tuple1(prefix + ":" + v)).toSeq
+      }.queryExecution.assertAnalyzed()
+    }
+    assert(e.getMessage.contains(
+      "Cannot explode *, explode can only be applied on a specific column."))
+
+    df.explode('prefix, 'csv) { case Row(prefix: String, csv: String) =>
+      csv.split(",").map(v => Tuple1(prefix + ":" + v)).toSeq
+    }.queryExecution.assertAnalyzed()
+  }
+
   test("explode alias and star") {
     val df = Seq((Array("a"), 1)).toDF("a", "b")