Writer.scala

    val writer = new ParquetWriter[Group](outFile, new GroupWriteSupport, codec, blockSize, pageSize, dictPageSize, true, true, ParquetProperties.WriterVersion.PARQUET_2_0, configuration)

    try {
      records.foreach { case ClientRecord(cid, diid, gwid, dvc, geo, timestamp, kvs) =>

        val group = new SimpleGroup(schema)
          .append("timestamp", timestamp)
          .append("cid", cid)
          .append("diid", diid)
          .append("gwid", gwid)
          .append("dvc", dvc)
          .append("geo", geo)

          val kvsGroup = group.addGroup("kvs")
          kvs.foreach { case (k,v) =>
            kvsGroup
              .addGroup("kv")
                .append("key",k)
                .append("value",v)
          }
        writer.write(group)
      }
    } finally writer.close()