spark-csv 中的自定义模式在 spark 1.4.1 中抛出错误

Question

我尝试在 spark 1.4.1 的 spark-shell 中使用 spark -csv 包处理 CSV 文件。

scala> import org.apache.spark.sql.hive.HiveContext                                                                                                  
import org.apache.spark.sql.hive.HiveContext                                                                                                         

scala> import org.apache.spark.sql.hive.orc._                                                                                                        
import org.apache.spark.sql.hive.orc._                                                                                                               

scala> import org.apache.spark.sql.types.{StructType, StructField, StringType, IntegerType};                                                         
import org.apache.spark.sql.types.{StructType, StructField, StringType, IntegerType}                                                                 

scala> val hiveContext = new org.apache.spark.sql.hive.HiveContext(sc)                                                                               
15/12/21 02:06:24 WARN SparkConf: The configuration key 'spark.yarn.applicationMaster.waitTries' has been deprecated as of Spark 1.3 and and may be removed in the future. Please use the new key 'spark.yarn.am.waitTime' instead.                                                                       
15/12/21 02:06:24 INFO HiveContext: Initializing execution hive, version 0.13.1                                                                      
hiveContext: org.apache.spark.sql.hive.HiveContext = org.apache.spark.sql.hive.HiveContext@74cba4b                                                   

scala> val customSchema = StructType(Seq(StructField("year", IntegerType, true),StructField("make", StringType, true),StructField("model", StringType, true),StructField("comment", StringType, true),StructField("blank", StringType, true)))
customSchema: org.apache.spark.sql.types.StructType = StructType(StructField(year,IntegerType,true), StructField(make,StringType,true), StructField(model,StringType,true), StructField(comment,StringType,true), StructField(blank,StringType,true))                                                     

scala> val customSchema = (new StructType).add("year", IntegerType, true).add("make", StringType, true).add("model", StringType, true).add("comment", StringType, true).add("blank", StringType, true)
:24: error: not enough arguments for constructor StructType: (fields: Array[org.apache.spark.sql.types.StructField])org.apache.spark.sql.types.StructType. Unspecified value parameter fields.                                                                                                                  

val customSchema = (new StructType).add("year", IntegerType, true).add("make", StringType, true).add("model", StringType,true).add("comment", StringType, true).add("blank", StringType, true)

Answer 1

根据 Spark 1.4.1 文档，StructType 没有无参数构造函数，这就是您收到错误的原因。您需要升级到 1.5.x 以获得无参数构造函数或按照您在第一个示例中建议的那样创建模式。

val customSchema = StructType(Seq(StructField("year", IntegerType, true),StructField("make", StringType, true),StructField("model", StringType, true),StructField("comment", StringType, true),StructField("blank", StringType, true)))

spark-csv 中的自定义模式在 spark 1.4.1 中抛出错误

Custom schema in spark-csv throwing error in spark 1.4.1

apache-spark

spark-dataframe

spark-csv