From 64d8f37c717cbc9c1c3649cae4c7cc4e628cd72d Mon Sep 17 00:00:00 2001
From: Dongjoon Hyun <dongjoon@apache.org>
Date: Mon, 1 Aug 2016 11:12:58 +0200
Subject: [SPARK-16726][SQL] Improve `Union/Intersect/Except` error messages on
 incompatible types

## What changes were proposed in this pull request?

Currently, `UNION` queries on incompatible types show misleading error messages, i.e., `unresolved operator Union`. We had better show a more correct message. This will help users in the situation of [SPARK-16704](https://issues.apache.org/jira/browse/SPARK-16704).

**Before**
```scala
scala> sql("select 1,2,3 union (select 1,array(2),3)")
org.apache.spark.sql.AnalysisException: unresolved operator 'Union;
scala> sql("select 1,2,3 intersect (select 1,array(2),3)")
org.apache.spark.sql.AnalysisException: unresolved operator 'Intersect;
scala> sql("select 1,2,3 except (select 1,array(2),3)")
org.apache.spark.sql.AnalysisException: unresolved operator 'Except;
```

**After**
```scala
scala> sql("select 1,2,3 union (select 1,array(2),3)")
org.apache.spark.sql.AnalysisException: Union can only be performed on tables with the compatible column types. ArrayType(IntegerType,false) <> IntegerType at the second column of the second table;
scala> sql("select 1,2,3 intersect (select 1,array(2),3)")
org.apache.spark.sql.AnalysisException: Intersect can only be performed on tables with the compatible column types. ArrayType(IntegerType,false) <> IntegerType at the second column of the second table;
scala> sql("select 1,2,3 except (select array(1),array(2),3)")
org.apache.spark.sql.AnalysisException: Except can only be performed on tables with the compatible column types. ArrayType(IntegerType,false) <> IntegerType at the first column of the second table;
```

## How was this patch tested?

Pass the Jenkins test with a new test case.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #14355 from dongjoon-hyun/SPARK-16726.
---
 .../sql/catalyst/analysis/CheckAnalysis.scala      | 44 +++++++++++++++-------
 1 file changed, 31 insertions(+), 13 deletions(-)

(limited to 'sql/catalyst/src/main')

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
index 8b87a4e41c..41b7e62d8c 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
@@ -253,19 +253,6 @@ trait CheckAnalysis extends PredicateHelper {
               }
             }
 
-          case s @ SetOperation(left, right) if left.output.length != right.output.length =>
-            failAnalysis(
-              s"${s.nodeName} can only be performed on tables with the same number of columns, " +
-                s"but the left table has ${left.output.length} columns and the right has " +
-                s"${right.output.length}")
-
-          case s: Union if s.children.exists(_.output.length != s.children.head.output.length) =>
-            val firstError = s.children.find(_.output.length != s.children.head.output.length).get
-            failAnalysis(
-              s"Unions can only be performed on tables with the same number of columns, " +
-                s"but one table has '${firstError.output.length}' columns and another table has " +
-                s"'${s.children.head.output.length}' columns")
-
           case GlobalLimit(limitExpr, _) => checkLimitClause(limitExpr)
 
           case LocalLimit(limitExpr, _) => checkLimitClause(limitExpr)
@@ -280,6 +267,37 @@ trait CheckAnalysis extends PredicateHelper {
           case p if p.expressions.exists(PredicateSubquery.hasPredicateSubquery) =>
             failAnalysis(s"Predicate sub-queries can only be used in a Filter: $p")
 
+          case _: Union | _: SetOperation if operator.children.length > 1 =>
+            def dataTypes(plan: LogicalPlan): Seq[DataType] = plan.output.map(_.dataType)
+            def ordinalNumber(i: Int): String = i match {
+              case 0 => "first"
+              case 1 => "second"
+              case i => s"${i}th"
+            }
+            val ref = dataTypes(operator.children.head)
+            operator.children.tail.zipWithIndex.foreach { case (child, ti) =>
+              // Check the number of columns
+              if (child.output.length != ref.length) {
+                failAnalysis(
+                  s"""
+                    |${operator.nodeName} can only be performed on tables with the same number
+                    |of columns, but the first table has ${ref.length} columns and
+                    |the ${ordinalNumber(ti + 1)} table has ${child.output.length} columns
+                  """.stripMargin.replace("\n", " ").trim())
+              }
+              // Check if the data types match.
+              dataTypes(child).zip(ref).zipWithIndex.foreach { case ((dt1, dt2), ci) =>
+                if (dt1 != dt2) {
+                  failAnalysis(
+                    s"""
+                      |${operator.nodeName} can only be performed on tables with the compatible
+                      |column types. $dt1 <> $dt2 at the ${ordinalNumber(ci)} column of
+                      |the ${ordinalNumber(ti + 1)} table
+                    """.stripMargin.replace("\n", " ").trim())
+                }
+              }
+            }
+
           case _ => // Fallbacks to the following checks
         }
 
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