i i在HBase表中有一个Rowkeys(植物(的集合,我想制作一个FetchData函数,该功能从集合中返回Rowkeys的RDD数据。目的是从fetchdata方法中为植物收集中的每种元素结合RDD。我给出了以下代码的相关部分。我的问题是,该代码为fetchdata的返回类型提供了编译错误:
println(partb:&quot hbaserdd.getnumpartitions(
错误:value getNumpArtitions不是选项的成员[org.apache.spark.rdd.rdd [it.nerdammer.spark.test.sys.sys.record]]
我正在使用Scala 2.11.8 Spark 2.2.0和Maven汇编
import it.nerdammer.spark.hbase._
import org.apache.spark.sql._
import org.apache.spark.sql.types.{StructType, StructField, StringType, IntegerType};
import org.apache.log4j.Level
import org.apache.log4j.Logger
import org.apache.spark.sql.SparkSession
import org.apache.spark.sql.functions._
object sys {
case class systems( rowkey: String, iacp: Option[String], temp: Option[String])
val spark = SparkSession.builder().appName("myApp").config("spark.executor.cores",4).getOrCreate()
import spark.implicits._
type Record = (String, Option[String], Option[String])
def fetchData(plant: String): RDD[Record] = {
val start_index = plant
val end_index = plant + "z"
//The below command works fine if I run it in main function, but to get multiple rows from hbase, I am using it in a separate function
spark.sparkContext.hbaseTable[Record]("test_table").select("iacp","temp").inColumnFamily("pp").withStartRow(start_index).withStopRow(end_index)
}
def main(args: Array[String]) {
//the below elements in the collection are prefix of relevant rowkeys in hbase table ("test_table")
val plants = Vector("a8","cu","aw","fx")
val hBaseRDD = plants.map( pp => fetchData(pp))
println("Part: "+ hBaseRDD.getNumPartitions)
/*
rest of the code
*/
}
}
这是代码的工作版本。这里的问题是我用于循环,我必须从每个循环中的HBase请求对应于Rowkey(Plant(向量的数据,而不是先获取所有数据,然后执行其余代码
import it.nerdammer.spark.hbase._
import org.apache.spark.sql._
import org.apache.spark.sql.types.{StructType, StructField, StringType, IntegerType};
import org.apache.log4j.Level
import org.apache.log4j.Logger
import org.apache.spark.sql.SparkSession
import org.apache.spark.sql.functions._
object sys {
case class systems( rowkey: String, iacp: Option[String], temp: Option[String])
def main(args: Array[String]) {
val spark = SparkSession.builder().appName("myApp").config("spark.executor.cores",4).getOrCreate()
import spark.implicits._
type Record = (String, Option[String], Option[String])
val plants = Vector("a8","cu","aw","fx")
for (plant <- plants){
val start_index = plant
val end_index = plant + "z"
val hBaseRDD = spark.sparkContext.hbaseTable[Record]("test_table").select("iacp","temp").inColumnFamily("pp").withStartRow(start_index).withStopRow(end_index)
println("Part: "+ hBaseRDD.getNumPartitions)
/*
rest of the code
*/
}
}
}
尝试后,这就是我现在被卡住的地方。因此,我该如何施放所需的类型。
scala> def fetchData(plant: String) = {
| val start_index = plant
| val end_index = plant + "~"
| val x1 = spark.sparkContext.hbaseTable[Record]("test_table").select("iacp","temp").inColumnFamily("pp").withStartRow(start_index).withStopRow(end_index)
| x1
| }
在repl and运行中定义功能
scala> val hBaseRDD = plants.map( pp => fetchData(pp)).reduceOption(_ union _)
<console>:39: error: type mismatch;
found : org.apache.spark.rdd.RDD[(String, Option[String], Option[String])]
required: it.nerdammer.spark.hbase.HBaseReaderBuilder[(String, Option[String], Option[String])]
val hBaseRDD = plants.map( pp => fetchData(pp)).reduceOption(_ union _)
预先感谢!
hBaseRDD
的类型是Vector[_]
而不是RDD[_]
,因此您无法在其上执行方法getNumPartitions
。如果我正确理解,您想联合获取RDD。您可以通过plants.map( pp => fetchData(pp)).reduceOption(_ union _)
执行此操作(我建议使用reduceOption
,因为它不会在空列表上失败,但是如果您确信该列表不是空的,则可以使用reduce
(
也返回的fetchData
类型是RDD[U]
,但我没有找到U
的任何定义。这可能是编译器推断Vector[Nothing]
而不是Vector[RDD[Record]]
的原因。为了避免随后的错误,您还应该将RDD[U]
更改为RDD[Record]
。