Spark: How can DataFrame be Dataset[Row] if DataFrame's have a schema

Question

This article claims that a DataFrame in Spark is equivalent to a Dataset[Row], but this blog post shows that a DataFrame has a schem

Answer 1

Note (in addition to the answer of T Gaweda) that there is a schema associated to each Row (Row.schema). However, this schema is not set until it is integrated in a DataFrame (or Dataset[Row])

scala> Row(1).schema
res12: org.apache.spark.sql.types.StructType = null

scala> val rdd = sc.parallelize(List(Row(1)))
rdd: org.apache.spark.rdd.RDD[org.apache.spark.sql.Row] = ParallelCollectionRDD[5] at parallelize at :28
scala> spark.createDataFrame(rdd,schema).first
res15: org.apache.spark.sql.Row = [1]
scala> spark.createDataFrame(rdd,schema).first.schema
res16: org.apache.spark.sql.types.StructType = StructType(StructField(a,IntegerType,true))