[GitHub] spark pull request: [SPARK-11856][SQL] add type cast if the real t...

[marmbrus <gi...@git.apache.org>]

Github user marmbrus commented on a diff in the pull request:

    https://github.com/apache/spark/pull/9840#discussion_r46224339
  
    --- Diff: sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/encoders/EncoderResolutionSuite.scala ---
    @@ -0,0 +1,165 @@
    +/*
    + * 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.encoders
    +
    +import scala.reflect.runtime.universe.TypeTag
    +
    +import org.apache.spark.sql.AnalysisException
    +import org.apache.spark.sql.catalyst.dsl.expressions._
    +import org.apache.spark.sql.catalyst.expressions._
    +import org.apache.spark.sql.catalyst.plans.PlanTest
    +import org.apache.spark.sql.types._
    +
    +case class StringLongClass(a: String, b: Long)
    +
    +case class StringIntClass(a: String, b: Int)
    +
    +case class ComplexClass(a: Long, b: StringLongClass)
    +
    +class EncoderResolutionSuite extends PlanTest {
    +  test("real type doesn't match encoder schema but they are compatible: product") {
    +    val encoder = ExpressionEncoder[StringLongClass]
    +    val cls = classOf[StringLongClass]
    +
    +    {
    +      val attrs = Seq('a.string, 'b.int)
    +      val fromRowExpr: Expression = encoder.resolve(attrs, null).fromRowExpression
    +      val expected: Expression = NewInstance(
    +        cls,
    +        toExternalString('a.string) :: 'b.int.cast(LongType) :: Nil,
    +        false,
    +        ObjectType(cls))
    +      compareExpressions(fromRowExpr, expected)
    +    }
    +
    +    {
    +      val attrs = Seq('a.int, 'b.long)
    +      val fromRowExpr = encoder.resolve(attrs, null).fromRowExpression
    +      val expected = NewInstance(
    +        cls,
    +        toExternalString('a.int.cast(StringType)) :: 'b.long :: Nil,
    +        false,
    +        ObjectType(cls))
    +      compareExpressions(fromRowExpr, expected)
    +    }
    +  }
    +
    +  test("real type doesn't match encoder schema but they are compatible: nested product") {
    +    val encoder = ExpressionEncoder[ComplexClass]
    +    val innerCls = classOf[StringLongClass]
    +    val cls = classOf[ComplexClass]
    +
    +    val structType = new StructType().add("a", IntegerType).add("b", LongType)
    +    val attrs = Seq('a.int, 'b.struct(structType))
    +    val fromRowExpr: Expression = encoder.resolve(attrs, null).fromRowExpression
    +    val expected: Expression = NewInstance(
    +      cls,
    +      Seq(
    +        'a.int.cast(LongType),
    +        If(
    +          'b.struct(structType).isNull,
    +          Literal.create(null, ObjectType(innerCls)),
    +          NewInstance(
    +            innerCls,
    +            Seq(
    +              toExternalString(
    +                GetStructField('b.struct(structType), 0, Some("a")).cast(StringType)),
    +              GetStructField('b.struct(structType), 1, Some("b"))),
    +            false,
    +            ObjectType(innerCls))
    +        )),
    +      false,
    +      ObjectType(cls))
    +    compareExpressions(fromRowExpr, expected)
    +  }
    +
    +  test("real type doesn't match encoder schema but they are compatible: tupled encoder") {
    +    val encoder = ExpressionEncoder.tuple(
    +      ExpressionEncoder[StringLongClass],
    +      ExpressionEncoder[Long])
    +    val cls = classOf[StringLongClass]
    +
    +    val structType = new StructType().add("a", StringType).add("b", ByteType)
    +    val attrs = Seq('a.struct(structType), 'b.int)
    +    val fromRowExpr: Expression = encoder.resolve(attrs, null).fromRowExpression
    +    val expected: Expression = NewInstance(
    +      classOf[Tuple2[_, _]],
    +      Seq(
    +        NewInstance(
    +          cls,
    +          Seq(
    +            toExternalString(GetStructField('a.struct(structType), 0, Some("a"))),
    +            GetStructField('a.struct(structType), 1, Some("b")).cast(LongType)),
    +          false,
    +          ObjectType(cls)),
    +        'b.int.cast(LongType)),
    +      false,
    +      ObjectType(classOf[Tuple2[_, _]]))
    +    compareExpressions(fromRowExpr, expected)
    +  }
    +
    +  private def toExternalString(e: Expression): Expression = {
    +    Invoke(e, "toString", ObjectType(classOf[String]), Nil)
    +  }
    +
    +  test("throw exception if real type is not compatible with encoder schema") {
    +    val msg1 = intercept[AnalysisException] {
    +      ExpressionEncoder[StringIntClass].resolve(Seq('a.string, 'b.long), null)
    +    }.message
    +    assert(msg1.contains("Cannot up cast `b` from bigint to int as it may truncate"))
    +
    +    val msg2 = intercept[AnalysisException] {
    +      val structType = new StructType().add("a", StringType).add("b", DecimalType.SYSTEM_DEFAULT)
    +      ExpressionEncoder[ComplexClass].resolve(Seq('a.long, 'b.struct(structType)), null)
    +    }.message
    +    assert(msg2.contains("Cannot up cast `b.b` from decimal(38,18) to bigint as it may truncate"))
    +
    +  }
    +
    +  // test for leaf types
    +  castSuccess[Int, Long]
    +  castSuccess[java.sql.Date, java.sql.Timestamp]
    +  castSuccess[Long, String]
    +  castSuccess[String, Long]
    --- End diff --
    
    Hmm, I'm torn.  I think users might be confused by a bunch of nulls.  I would say no and we can always add that later.


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