Spark2.3.1使用技巧

Spark 2.3.1 使用技巧

Spark-SQL 读取JSON文件时反射表头

case class StudentInfo(id:Long,name:String,age:Int)

val example = spark.read.json("/data/result.json").as(StudentInfo)
example.show()

动态定义schema

在须要根据不一样数据定义不一样schema

val schemaInfo = "name age"
val fields = schemaInfo.map(item=> item.split(" ")
     .map(item=>StructField(item,StringType,nullable=true))
val schema = StructType(fields)

val rowRDD = peopleRDD.map(_.split(" ").map(attributes=>Row(attributes(0),attributes(1))

val peopleDF = spark.createDataFrame(rowRDD,schema)

peopleDF.show()

Spark 2.3.1 on YARN

spark-submit 限制参数未生效

由于在spark-submit时配置的executor-memory 2g等没有生效，后来问同事说他也碰到这样的问题，解决方案就是动态的分配executor,官方文档,中文文档

--conf spark.yarn.maxAppAttempts=1 --conf spark.dynamicAllocation.minExecutors=2 --conf spark.dynamicAllocation.maxExecutors=4 --conf spark.dynamicAllocation.initialExecutors=4