Sam De Backer created SPARK-23959:
-------------------------------------
Summary: UnresolvedException with DataSet created from Seq.empty
since Spark 2.3.0
Key: SPARK-23959
URL: https://issues.apache.org/jira/browse/SPARK-23959
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 2.3.0
Reporter: Sam De Backer
The following snippet works fine in Spark 2.2.1 but gives a rather cryptic
runtime exception in Spark 2.3.0:
{code:java}
import sparkSession.implicits._
import org.apache.spark.sql.functions._
case class X(xid: Long, yid: Int)
case class Y(yid: Int, zid: Long)
case class Z(zid: Long, b: Boolean)
val xs = Seq(X(1L, 10)).toDS()
val ys = Seq(Y(10, 100L)).toDS()
val zs = Seq.empty[Z].toDS()
val j = xs
.join(ys, "yid")
.join(zs, Seq("zid"), "left")
.withColumn("BAM", when('b, "B").otherwise("NB"))
j.show(){code}
In Spark 2.2.1 it prints to the console
{noformat}
+---+---+---+----+---+
|zid|yid|xid| b|BAM|
+---+---+---+----+---+
|100| 10| 1|null| NB|
+---+---+---+----+---+{noformat}
In Spark 2.3.0 it results in:
{noformat}
org.apache.spark.sql.catalyst.analysis.UnresolvedException: Invalid call to
dataType on unresolved object, tree: 'BAM
at
org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute.dataType(unresolved.scala:105)
at
org.apache.spark.sql.types.StructType$$anonfun$fromAttributes$1.apply(StructType.scala:435)
at
org.apache.spark.sql.types.StructType$$anonfun$fromAttributes$1.apply(StructType.scala:435)
at
scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
at
scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
at scala.collection.immutable.List.foreach(List.scala:392)
at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
at scala.collection.immutable.List.map(List.scala:296)
at org.apache.spark.sql.types.StructType$.fromAttributes(StructType.scala:435)
at
org.apache.spark.sql.catalyst.plans.QueryPlan.schema$lzycompute(QueryPlan.scala:157)
...{noformat}
The culprit really seems to be DataSet being created from an empty Seq[Z]. When
you change that to something that will also result in an empty DataSet[Z] it
works as in Spark 2.2.1, e.g.
{code:java}
val zs = Seq(Z(10L, true)).toDS().filter('zid === Long.MinValue){code}
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