scala> val emp = spark.emptyDataset[Seq[String]]
emp: org.apache.spark.sql.Dataset[Seq[String]] = [value: array<string>]

scala> emp.select(explode($"value")).show
+---+
|col|
+---+
+---+

scala> emp.select(explode($"value")).explain(true)
== Parsed Logical Plan ==
'Project [explode('value) AS List()]
+- LocalRelation <empty>, [value#77]

== Analyzed Logical Plan ==
col: string
Project [col#89]
+- Generate explode(value#77), false, false, [col#89]
   +- LocalRelation <empty>, [value#77]

== Optimized Logical Plan ==
LocalRelation <empty>, [col#89]

== Physical Plan ==
LocalTableScan <empty>, [col#89]

scala> spark.emptyDataset[Int].join(spark.range(1)).explain(extended = true)
...
TRACE SparkOptimizer:
=== Applying Rule org.apache.spark.sql.catalyst.optimizer.PropagateEmptyRelation ===
!Join Inner                                LocalRelation <empty>, [value#40, id#42L]
!:- LocalRelation <empty>, [value#40]
!+- Range (0, 1, step=1, splits=Some(8))

TRACE SparkOptimizer: Fixed point reached for batch LocalRelation after 2 iterations.
DEBUG SparkOptimizer:
=== Result of Batch LocalRelation ===
!Join Inner                                LocalRelation <empty>, [value#40, id#42L]
!:- LocalRelation <empty>, [value#40]
!+- Range (0, 1, step=1, splits=Some(8))
...
== Parsed Logical Plan ==
Join Inner
:- LocalRelation <empty>, [value#40]
+- Range (0, 1, step=1, splits=Some(8))

== Analyzed Logical Plan ==
value: int, id: bigint
Join Inner
:- LocalRelation <empty>, [value#40]
+- Range (0, 1, step=1, splits=Some(8))

== Optimized Logical Plan ==
LocalRelation <empty>, [value#40, id#42L]

== Physical Plan ==
LocalTableScan <empty>, [value#40, id#42L]