added union check rule

Author: scwf

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala

@@ -105,6 +105,18 @@ trait CheckAnalysis {
 
             cleaned.foreach(checkValidAggregateExpression)
 
+          case u @ Union(left, right) if left.output.size != right.output.size =>
+            failAnalysis(
+              s"union's left child and right child have different output size. " +
+                s"union node: $u left output size: ${left.output.size}, " +
+                  s"right output size: ${right.output.size}")
+
+          case u @ Union(left, right) if left.output.zip(right.output).exists(z => z._1.dataType != z._2.dataType) =>
+            failAnalysis(
+              s"union's left child and right child have different output types." +
+                s"union node: $u. left output datatypes: ${left.output.map(_.dataType)}, " +
+                  s"right output datatypes: ${right.output.map(_.dataType)}")
+
           case _ => // Fallbacks to the following checks
         }