Spark：以 ORC 格式保存数据框

Question

在之前的版本中，我们曾经在 RDD 上有一个 'saveAsOrcFile()' 方法。现在没有了！如何以 ORC 文件格式保存 DataFrame 中的数据？

def main(args: Array[String]) {
println("Creating Orc File!")
val sparkConf = new SparkConf().setAppName("orcfile")
val sc = new SparkContext(sparkConf)
val hiveContext = new org.apache.spark.sql.hive.HiveContext(sc)

val people = sc.textFile("/apps/testdata/people.txt")
val schemaString = "name age"
val schema = StructType(schemaString.split(" ").map(fieldName => {if(fieldName == "name") StructField(fieldName, StringType, true) else StructField(fieldName, IntegerType, true)}))
val rowRDD = people.map(_.split(",")).map(p => Row(p(0), new Integer(p(1).trim)))

//# Infer table schema from RDD**
val peopleSchemaRDD = hiveContext.createDataFrame(rowRDD, schema)

//# Create a table from schema**
peopleSchemaRDD.registerTempTable("people")
val results = hiveContext.sql("SELECT * FROM people")
results.map(t => "Name: " + t.toString).collect().foreach(println)

// Now I want to save this Dataframe(peopleSchemaRDD) in ORC Format. How do I do that?

}

Answer 1

从 Spark 1.4 开始，您可以简单地使用 DataFrameWriter 并将 format 设置为 orc：

peopleSchemaRDD.write.format("orc").save("people")

或

peopleSchemaRDD.write.orc("people")