[jira] [Created] (SPARK-6587) Inferring schema for case class hierarchy fails with mysterious message

[Spiro Michaylov (JIRA)]

Spiro Michaylov created SPARK-6587:
--------------------------------------

             Summary: Inferring schema for case class hierarchy fails with 
mysterious message
                 Key: SPARK-6587
                 URL: https://issues.apache.org/jira/browse/SPARK-6587
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 1.3.0
         Environment: At least Windows 8, Scala 2.11.2.  
            Reporter: Spiro Michaylov


(Don't know if this is a functionality bug, error reporting bug or an RFE ...)

I define the following hierarchy:

{code}
    private abstract class MyHolder
    private case class StringHolder(s: String) extends MyHolder
    private case class IntHolder(i: Int) extends MyHolder
    private case class BooleanHolder(b: Boolean) extends MyHolder
{code}

and a top level case class:

{code}
    private case class Thing(key: Integer, foo: MyHolder)
{code}

When I try to convert it:

{code}
    val things = Seq(
      Thing(1, IntHolder(42)),
      Thing(2, StringHolder("hello")),
      Thing(3, BooleanHolder(false))
    )
    val thingsDF = sc.parallelize(things, 4).toDF()

    thingsDF.registerTempTable("things")

    val all = sqlContext.sql("SELECT * from things")
{code}

I get the following stack trace:

{quote}
Exception in thread "main" scala.MatchError: 
sql.CaseClassSchemaProblem.MyHolder (of class 
scala.reflect.internal.Types$ClassNoArgsTypeRef)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$class.schemaFor(ScalaReflection.scala:112)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$.schemaFor(ScalaReflection.scala:30)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$$anonfun$schemaFor$1.apply(ScalaReflection.scala:159)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$$anonfun$schemaFor$1.apply(ScalaReflection.scala:157)
        at scala.collection.immutable.List.map(List.scala:276)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$class.schemaFor(ScalaReflection.scala:157)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$.schemaFor(ScalaReflection.scala:30)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$class.schemaFor(ScalaReflection.scala:107)
        at 
org.apache.spark.sql.catalyst.ScalaReflection$.schemaFor(ScalaReflection.scala:30)
        at org.apache.spark.sql.SQLContext.createDataFrame(SQLContext.scala:312)
        at 
org.apache.spark.sql.SQLContext$implicits$.rddToDataFrameHolder(SQLContext.scala:250)
        at sql.CaseClassSchemaProblem$.main(CaseClassSchemaProblem.scala:35)
        at sql.CaseClassSchemaProblem.main(CaseClassSchemaProblem.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)
{quote}

I wrote this to answer [a question on 
StackOverflow|http://stackoverflow.com/questions/29310405/what-is-the-right-way-to-represent-an-any-type-in-spark-sql]
 which uses a much simpler approach and suffers the same problem.

Looking at what seems to me to be the [relevant unit test 
suite|https://github.com/apache/spark/blob/master/sql/core/src/test/scala/org/apache/spark/sql/ScalaReflectionRelationSuite.scala]
 I see that this case is not covered.  



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