[SPARK-7562][SPARK-6444][SQL] Improve error reporting for expression data type mismatch

It seems hard to find a common pattern of checking types in `Expression`. Sometimes we know what input types we need(like `And`, we know we need two booleans), sometimes we just have some rules(like `Add`, we need 2 numeric types which are equal). So I defined a general interface `checkInputDataTypes` in `Expression` which returns a `TypeCheckResult`. `TypeCheckResult` can tell whether this expression passes the type checking or what the type mismatch is.

This PR mainly works on apply input types checking for arithmetic and predicate expressions.

TODO: apply type checking interface to more expressions.

Author: Wenchen Fan <[email protected]>

Closes #6405 from cloud-fan/6444 and squashes the following commits:

b5ff31b [Wenchen Fan] address comments
b917275 [Wenchen Fan] rebase
39929d9 [Wenchen Fan] add todo
0808fd2 [Wenchen Fan] make constrcutor of TypeCheckResult private
3bee157 [Wenchen Fan] and decimal type coercion rule for binary comparison
8883025 [Wenchen Fan] apply type check interface to CaseWhen
cffb67c [Wenchen Fan] to have resolved call the data type check function
6eaadff [Wenchen Fan] add equal type constraint to EqualTo
3affbd8 [Wenchen Fan] more fixes
654d46a [Wenchen Fan] improve tests
e0a3628 [Wenchen Fan] improve error message
1524ff6 [Wenchen Fan] fix style
69ca3fe [Wenchen Fan] add error message and tests
c71d02c [Wenchen Fan] fix hive tests
6491721 [Wenchen Fan] use value class TypeCheckResult
7ae76b9 [Wenchen Fan] address comments
cb77e4f [Wenchen Fan] Improve error reporting for expression data type mismatch

Author: cloud-fan

core/src/test/scala/org/apache/spark/SparkFunSuite.scala

@@ -30,8 +30,8 @@ private[spark] abstract class SparkFunSuite extends FunSuite with Logging {
    * Log the suite name and the test name before and after each test.
    *
    * Subclasses should never override this method. If they wish to run
-   * custom code before and after each test, they should should mix in
-   * the {{org.scalatest.BeforeAndAfter}} trait instead.
+   * custom code before and after each test, they should mix in the
+   * {{org.scalatest.BeforeAndAfter}} trait instead.
    */
   final protected override def withFixture(test: NoArgTest): Outcome = {
     val testName = test.text

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

@@ -62,15 +62,17 @@ trait CheckAnalysis {
             val from = operator.inputSet.map(_.name).mkString(", ")
             a.failAnalysis(s"cannot resolve '${a.prettyString}' given input columns $from")
 
+          case e: Expression if e.checkInputDataTypes().isFailure =>
+            e.checkInputDataTypes() match {
+              case TypeCheckResult.TypeCheckFailure(message) =>
+                e.failAnalysis(
+                  s"cannot resolve '${e.prettyString}' due to data type mismatch: $message")
+            }
+
           case c: Cast if !c.resolved =>
             failAnalysis(
               s"invalid cast from ${c.child.dataType.simpleString} to ${c.dataType.simpleString}")
 
-          case b: BinaryExpression if !b.resolved =>
-            failAnalysis(
-              s"invalid expression ${b.prettyString} " +
-              s"between ${b.left.dataType.simpleString} and ${b.right.dataType.simpleString}")
-
           case WindowExpression(UnresolvedWindowFunction(name, _), _) =>
             failAnalysis(
               s"Could not resolve window function '$name'. " +

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

@@ -41,7 +41,7 @@ object HiveTypeCoercion {
    * with primitive types, because in that case the precision and scale of the result depends on
    * the operation. Those rules are implemented in [[HiveTypeCoercion.DecimalPrecision]].
    */
-  val findTightestCommonType: (DataType, DataType) => Option[DataType] = {
+  val findTightestCommonTypeOfTwo: (DataType, DataType) => Option[DataType] = {
     case (t1, t2) if t1 == t2 => Some(t1)
     case (NullType, t1) => Some(t1)
     case (t1, NullType) => Some(t1)
@@ -57,6 +57,17 @@ object HiveTypeCoercion {
 
     case _ => None
   }
+
+  /**
+   * Find the tightest common type of a set of types by continuously applying
+   * `findTightestCommonTypeOfTwo` on these types.
+   */
+  private def findTightestCommonType(types: Seq[DataType]) = {
+    types.foldLeft[Option[DataType]](Some(NullType))((r, c) => r match {
+      case None => None
+      case Some(d) => findTightestCommonTypeOfTwo(d, c)
+    })
+  }
 }
 
 /**
@@ -180,7 +191,7 @@ trait HiveTypeCoercion {
 
           case (l, r) if l.dataType != r.dataType =>
             logDebug(s"Resolving mismatched union input ${l.dataType}, ${r.dataType}")
-            findTightestCommonType(l.dataType, r.dataType).map { widestType =>
+            findTightestCommonTypeOfTwo(l.dataType, r.dataType).map { widestType =>
               val newLeft =
                 if (l.dataType == widestType) l else Alias(Cast(l, widestType), l.name)()
               val newRight =
@@ -217,7 +228,7 @@ trait HiveTypeCoercion {
         case e if !e.childrenResolved => e
 
         case b: BinaryExpression if b.left.dataType != b.right.dataType =>
-          findTightestCommonType(b.left.dataType, b.right.dataType).map { widestType =>
+          findTightestCommonTypeOfTwo(b.left.dataType, b.right.dataType).map { widestType =>
             val newLeft =
               if (b.left.dataType == widestType) b.left else Cast(b.left, widestType)
             val newRight =
@@ -441,21 +452,18 @@ trait HiveTypeCoercion {
             DecimalType(min(p1 - s1, p2 - s2) + max(s1, s2), max(s1, s2))
           )
 
-        case LessThan(e1 @ DecimalType.Expression(p1, s1),
-                      e2 @ DecimalType.Expression(p2, s2)) if p1 != p2 || s1 != s2 =>
-          LessThan(Cast(e1, DecimalType.Unlimited), Cast(e2, DecimalType.Unlimited))
-
-        case LessThanOrEqual(e1 @ DecimalType.Expression(p1, s1),
-                             e2 @ DecimalType.Expression(p2, s2)) if p1 != p2 || s1 != s2 =>
-          LessThanOrEqual(Cast(e1, DecimalType.Unlimited), Cast(e2, DecimalType.Unlimited))
-
-        case GreaterThan(e1 @ DecimalType.Expression(p1, s1),
-                         e2 @ DecimalType.Expression(p2, s2)) if p1 != p2 || s1 != s2 =>
-          GreaterThan(Cast(e1, DecimalType.Unlimited), Cast(e2, DecimalType.Unlimited))
-
-        case GreaterThanOrEqual(e1 @ DecimalType.Expression(p1, s1),
-                                e2 @ DecimalType.Expression(p2, s2)) if p1 != p2 || s1 != s2 =>
-          GreaterThanOrEqual(Cast(e1, DecimalType.Unlimited), Cast(e2, DecimalType.Unlimited))
+        // When we compare 2 decimal types with different precisions, cast them to the smallest
+        // common precision.
+        case b @ BinaryComparison(e1 @ DecimalType.Expression(p1, s1),
+                                  e2 @ DecimalType.Expression(p2, s2)) if p1 != p2 || s1 != s2 =>
+          val resultType = DecimalType(max(p1, p2), max(s1, s2))
+          b.makeCopy(Array(Cast(e1, resultType), Cast(e2, resultType)))
+        case b @ BinaryComparison(e1 @ DecimalType.Fixed(_, _), e2)
+          if e2.dataType == DecimalType.Unlimited =>
+          b.makeCopy(Array(Cast(e1, DecimalType.Unlimited), e2))
+        case b @ BinaryComparison(e1, e2 @ DecimalType.Fixed(_, _))
+          if e1.dataType == DecimalType.Unlimited =>
+          b.makeCopy(Array(e1, Cast(e2, DecimalType.Unlimited)))
 
         // Promote integers inside a binary expression with fixed-precision decimals to decimals,
         // and fixed-precision decimals in an expression with floats / doubles to doubles
@@ -570,7 +578,7 @@ trait HiveTypeCoercion {
 
       case a @ CreateArray(children) if !a.resolved =>
         val commonType = a.childTypes.reduce(
-          (a, b) => findTightestCommonType(a, b).getOrElse(StringType))
+          (a, b) => findTightestCommonTypeOfTwo(a, b).getOrElse(StringType))
         CreateArray(
           children.map(c => if (c.dataType == commonType) c else Cast(c, commonType)))
 
@@ -599,14 +607,9 @@ trait HiveTypeCoercion {
       // from the list. So we need to make sure the return type is deterministic and
       // compatible with every child column.
       case Coalesce(es) if es.map(_.dataType).distinct.size > 1 =>
-        val dt: Option[DataType] = Some(NullType)
         val types = es.map(_.dataType)
-        val rt = types.foldLeft(dt)((r, c) => r match {
-          case None => None
-          case Some(d) => findTightestCommonType(d, c)
-        })
-        rt match {
-          case Some(finaldt) => Coalesce(es.map(Cast(_, finaldt)))
+        findTightestCommonType(types) match {
+          case Some(finalDataType) => Coalesce(es.map(Cast(_, finalDataType)))
           case None =>
             sys.error(s"Could not determine return type of Coalesce for ${types.mkString(",")}")
         }
@@ -619,17 +622,13 @@ trait HiveTypeCoercion {
    */
   object Division extends Rule[LogicalPlan] {
     def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
-      // Skip nodes who's children have not been resolved yet.
-      case e if !e.childrenResolved => e
+      // Skip nodes who has not been resolved yet,
+      // as this is an extra rule which should be applied at last.
+      case e if !e.resolved => e
 
       // Decimal and Double remain the same
-      case d: Divide if d.resolved && d.dataType == DoubleType => d
-      case d: Divide if d.resolved && d.dataType.isInstanceOf[DecimalType] => d
-
-      case Divide(l, r) if l.dataType.isInstanceOf[DecimalType] =>
-        Divide(l, Cast(r, DecimalType.Unlimited))
-      case Divide(l, r) if r.dataType.isInstanceOf[DecimalType] =>
-        Divide(Cast(l, DecimalType.Unlimited), r)
+      case d: Divide if d.dataType == DoubleType => d
+      case d: Divide if d.dataType.isInstanceOf[DecimalType] => d
 
       case Divide(l, r) => Divide(Cast(l, DoubleType), Cast(r, DoubleType))
     }
@@ -642,42 +641,33 @@ trait HiveTypeCoercion {
     import HiveTypeCoercion._
 
     def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
-      case cw: CaseWhenLike if cw.childrenResolved && !cw.valueTypesEqual =>
-        logDebug(s"Input values for null casting ${cw.valueTypes.mkString(",")}")
-        val commonType = cw.valueTypes.reduce { (v1, v2) =>
-          findTightestCommonType(v1, v2).getOrElse(sys.error(
-            s"Types in CASE WHEN must be the same or coercible to a common type: $v1 != $v2"))
-        }
-        val transformedBranches = cw.branches.sliding(2, 2).map {
-          case Seq(when, value) if value.dataType != commonType =>
-            Seq(when, Cast(value, commonType))
-          case Seq(elseVal) if elseVal.dataType != commonType =>
-            Seq(Cast(elseVal, commonType))
-          case s => s
-        }.reduce(_ ++ _)
-        cw match {
-          case _: CaseWhen =>
-            CaseWhen(transformedBranches)
-          case CaseKeyWhen(key, _) =>
-            CaseKeyWhen(key, transformedBranches)
-        }
-
-      case ckw: CaseKeyWhen if ckw.childrenResolved && !ckw.resolved =>
-        val commonType = (ckw.key +: ckw.whenList).map(_.dataType).reduce { (v1, v2) =>
-          findTightestCommonType(v1, v2).getOrElse(sys.error(
-            s"Types in CASE WHEN must be the same or coercible to a common type: $v1 != $v2"))
-        }
-        val transformedBranches = ckw.branches.sliding(2, 2).map {
-          case Seq(when, then) if when.dataType != commonType =>
-            Seq(Cast(when, commonType), then)
-          case s => s
-        }.reduce(_ ++ _)
-        val transformedKey = if (ckw.key.dataType != commonType) {
-          Cast(ckw.key, commonType)
-        } else {
-          ckw.key
-        }
-        CaseKeyWhen(transformedKey, transformedBranches)
+      case c: CaseWhenLike if c.childrenResolved && !c.valueTypesEqual =>
+        logDebug(s"Input values for null casting ${c.valueTypes.mkString(",")}")
+        val maybeCommonType = findTightestCommonType(c.valueTypes)
+        maybeCommonType.map { commonType =>
+          val castedBranches = c.branches.grouped(2).map {
+            case Seq(when, value) if value.dataType != commonType =>
+              Seq(when, Cast(value, commonType))
+            case Seq(elseVal) if elseVal.dataType != commonType =>
+              Seq(Cast(elseVal, commonType))
+            case other => other
+          }.reduce(_ ++ _)
+          c match {
+            case _: CaseWhen => CaseWhen(castedBranches)
+            case CaseKeyWhen(key, _) => CaseKeyWhen(key, castedBranches)
+          }
+        }.getOrElse(c)
+
+      case c: CaseKeyWhen if c.childrenResolved && !c.resolved =>
+        val maybeCommonType = findTightestCommonType((c.key +: c.whenList).map(_.dataType))
+        maybeCommonType.map { commonType =>
+          val castedBranches = c.branches.grouped(2).map {
+            case Seq(when, then) if when.dataType != commonType =>
+              Seq(Cast(when, commonType), then)
+            case other => other
+          }.reduce(_ ++ _)
+          CaseKeyWhen(Cast(c.key, commonType), castedBranches)
+        }.getOrElse(c)
     }
   }
 

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

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.catalyst.analysis
+
+/**
+ * Represents the result of `Expression.checkInputDataTypes`.
+ * We will throw `AnalysisException` in `CheckAnalysis` if `isFailure` is true.
+ */
+trait TypeCheckResult {
+  def isFailure: Boolean = !isSuccess
+  def isSuccess: Boolean
+}
+
+object TypeCheckResult {
+
+  /**
+   * Represents the successful result of `Expression.checkInputDataTypes`.
+   */
+  object TypeCheckSuccess extends TypeCheckResult {
+    def isSuccess: Boolean = true
+  }
+
+  /**
+   * Represents the failing result of `Expression.checkInputDataTypes`,
+   * with a error message to show the reason of failure.
+   */
+  case class TypeCheckFailure(message: String) extends TypeCheckResult {
+    def isSuccess: Boolean = false
+  }
+}

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala

@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
-import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
+import org.apache.spark.sql.catalyst.analysis.{TypeCheckResult, UnresolvedAttribute}
 import org.apache.spark.sql.catalyst.trees
 import org.apache.spark.sql.catalyst.trees.TreeNode
 import org.apache.spark.sql.types._
@@ -53,11 +53,12 @@ abstract class Expression extends TreeNode[Expression] {
 
   /**
    * Returns `true` if this expression and all its children have been resolved to a specific schema
-   * and `false` if it still contains any unresolved placeholders. Implementations of expressions
-   * should override this if the resolution of this type of expression involves more than just
-   * the resolution of its children.
+   * and input data types checking passed, and `false` if it still contains any unresolved
+   * placeholders or has data types mismatch.
+   * Implementations of expressions should override this if the resolution of this type of
+   * expression involves more than just the resolution of its children and type checking.
    */
-  lazy val resolved: Boolean = childrenResolved
+  lazy val resolved: Boolean = childrenResolved && checkInputDataTypes().isSuccess
 
   /**
    * Returns the [[DataType]] of the result of evaluating this expression.  It is
@@ -94,12 +95,21 @@ abstract class Expression extends TreeNode[Expression] {
       case (i1, i2) => i1 == i2
     }
   }
+
+  /**
+   * Checks the input data types, returns `TypeCheckResult.success` if it's valid,
+   * or returns a `TypeCheckResult` with an error message if invalid.
+   * Note: it's not valid to call this method until `childrenResolved == true`
+   * TODO: we should remove the default implementation and implement it for all
+   * expressions with proper error message.
+   */
+  def checkInputDataTypes(): TypeCheckResult = TypeCheckResult.TypeCheckSuccess
 }
 
 abstract class BinaryExpression extends Expression with trees.BinaryNode[Expression] {
   self: Product =>
 
-  def symbol: String
+  def symbol: String = sys.error(s"BinaryExpressions must override either toString or symbol")
 
   override def foldable: Boolean = left.foldable && right.foldable
 
@@ -133,7 +143,13 @@ case class GroupExpression(children: Seq[Expression]) extends Expression {
  * so that the proper type conversions can be performed in the analyzer.
  */
 trait ExpectsInputTypes {
+  self: Expression =>
 
   def expectedChildTypes: Seq[DataType]
 
+  override def checkInputDataTypes(): TypeCheckResult = {
+    // We will always do type casting for `ExpectsInputTypes` in `HiveTypeCoercion`,
+    // so type mismatch error won't be reported here, but for underling `Cast`s.
+    TypeCheckResult.TypeCheckSuccess
+  }
 }