scala Spark：以 ORC 格式保存数据帧
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时间：2020-10-22 07:36:44 来源:igfitidea点击:
Spark: Save Dataframe in ORC format
提问by DilTeam
In the previous version, we used to have a 'saveAsOrcFile()' method on RDD. This is now gone! How do I save data in DataFrame in ORC File format?
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 文件格式将数据保存在 DataFrame 中？
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?
}
}
回答by zero323
Since Spark 1.4 you can simply use DataFrameWriterand set formatto orc:
从 Spark 1.4 开始，您可以简单地使用DataFrameWriter并设置format为orc：
peopleSchemaRDD.write.format("orc").save("people")
or
或者
peopleSchemaRDD.write.orc("people")
