Figured it out ... needed to use saveAsNewAPIHadoopFile, but was trying to use it on myDF.rdd instead of converting it to a PairRDD first.

On Mon, Oct 19, 2015 at 2:14 PM, Alex Nastetsky <alex.nastetsky@vervemobile.com> wrote:
Using Spark 1.5.1, Parquet 1.7.0.

I'm trying to write Avro/Parquet files. I have this code:

sc.hadoopConfiguration.set(ParquetOutputFormat.WRITE_SUPPORT_CLASS, classOf[AvroWriteSupport].getName)
AvroWriteSupport.setSchema(sc.hadoopConfiguration, MyClass.SCHEMA$)
myDF.write.parquet(outputPath)

The problem is that the write support class gets overwritten in org.apache.spark.sql.execution.datasources.parquet.ParquetRelation#prepareJobForWrite:

val writeSupportClass =
if (dataSchema.map(_.dataType).forall(ParquetTypesConverter.isPrimitiveType)) {
classOf[MutableRowWriteSupport]
} else {
classOf[RowWriteSupport]
}
ParquetOutputFormat.setWriteSupportClass(job, writeSupportClass)

So it doesn't seem to actually write Avro data. When look at the metadata of the Parquet files it writes, it looks like this:

extra:             org.apache.spark.sql.parquet.row.metadata = {"type":"struct","fields":[{"name":"foo","type":"string","nullable":true,"metadata":{}},{"name":"bar","type":"long","nullable":true,"metadata":{}}]} 

I would expect to see something like "extra:  avro.schema" instead.