Question

我想从2个不同的Mongo数据库中制作2个数据集。我目前正在使用官方MongoSpark连接器。 sparkSession以下列方式启动。

SparkConf sparkConf = new SparkConf().setMaster("yarn").setAppName("test")
                        .set("spark.mongodb.input.partitioner", "MongoShardedPartitioner")
                        .set("spark.mongodb.input.uri", "mongodb://192.168.77.62/db1.coll1")
                        .set("spark.sql.crossJoin.enabled", "true");
SparkSession sparkSession = sparkSession.builder().appName("test1").config(sparkConf).getOrCreate();

如果我想更改spark.mongodb.input.uri，我该怎么做？我已经尝试更改sparkSession的runtimeConfig，并将readConfig与readOverrides一起使用，但这些不起作用。

方法1：

sparkSession.conf().set("spark.mongodb.input.uri", "mongodb://192.168.77.63/db1.coll2");

方法2：

Map<String, String> readOverrides = new HashMap<String, String>();
readoverrides.put("uri","192.168.77.63/db1.coll2");
ReadConfig readConfig = ReadConfig.create(sparkSession).withOptions(readOverrides);
Dataset<Position> ds = MongoSpark.load(sparkSession, readConfig, Position.class);

编辑1：正如Karol所建议我尝试了以下方法

  SparkConf sparkConf = new SparkConf().setMaster("yarn").setAppName("test");
SparkSession sparkSession = SparkSession.builder().appName("test1").config(sparkConf).getOrCreate();
    Map<String, String> readOverrides1 = new HashMap<String, String>();
            readOverrides1.put("uri", "mongodb://192.168.77.62:27017");
            readOverrides1.put("database", "db1");
            readOverrides1.put("collection", "coll1");
            ReadConfig readConfig = ReadConfig.create(sparkSession).withOptions(readOverrides1);

这在运行时失败说：

Exception in thread "main" java.lang.IllegalArgumentException: Missing database name. Set via the 'spark.mongodb.input.uri' or 'spark.mongodb.input.database' property

编辑2：

public static void main(String[] args) {
    SparkSession sparkSession = SparkSession.builder().appName("test")
            .config("spark.worker.cleanup.enabled", "true").config("spark.scheduler.mode", "FAIR").getOrCreate();
    String mongoURI2 = "mongodb://192.168.77.63:27017/db1.coll1";
    Map<String, String> readOverrides1 = new HashMap<String, String>();
    readOverrides1.put("uri", mongoURI2);
    ReadConfig readConfig1 = ReadConfig.create(sparkSession).withOptions(readOverrides1);
    MongoSpark.load(sparkSession,readConfig1,Position.class).show();
}

这仍然是与上一次编辑相同的例外。

Answer 1

built.sbt： libraryDependencies += "org.mongodb.spark" % "mongo-spark-connector_2.11" % "2.0.0"

 package com.example.app

 import com.mongodb.spark.config.{ReadConfig, WriteConfig}
 import com.mongodb.spark.sql._

object App {


 def main(args: Array[String]): Unit = {

    val MongoUri1 = args(0).toString
    val MongoUri2 = args(1).toString
    val SparkMasterUri= args(2).toString

     def makeMongoURI(uri:String,database:String,collection:String) = (s"${uri}/${database}.${collection}")

   val mongoURI1 = s"mongodb://${MongoUri1}:27017"
   val mongoURI2 = s"mongodb://${MongoUri2}:27017"

   val CONFdb1 = makeMongoURI(s"${mongoURI1}","MyColletion1,"df")
   val CONFdb2 = makeMongoURI(s"${mongoURI2}","MyColletion2,"df")

   val WRITEdb1: WriteConfig =  WriteConfig(scala.collection.immutable.Map("uri"->CONFdb1))
   val READdb1: ReadConfig = ReadConfig(Map("uri" -> CONFdb1))

   val WRITEdb2: WriteConfig =  WriteConfig(scala.collection.immutable.Map("uri"->CONFdb2))
   val READdb2: ReadConfig = ReadConfig(Map("uri" -> CONFdb2))

   val spark = SparkSession
  .builder
  .appName("AppMongo")
  .config("spark.worker.cleanup.enabled", "true")
  .config("spark.scheduler.mode", "FAIR")
  .getOrCreate()

   val df1 = spark.read.mongo(READdb1)
   val df2 = spark.read.mongo(READdb2)
   df1.write.mode("overwrite").mongo(WRITEdb1)
   df2.write.mode("overwrite").mongo(WRITEdb2)

 }

}

您现在可以将uri1和uri2作为参数传递到/usr/local/spark/bin/spark-submit pathToMyjar.app.jar MongoUri1 MongoUri2 sparkMasterUri，然后为每个config创建uri

spark.read.mongo(READdb)

Answer 2

在ReadConfig中设置uri是没有用的。当调用ReadConfig.create（）方法时，Spark-Mongo连接器将使用此信息。因此，在使用它之前，请尝试在SparkContext中进行设置。

就像下面这样：

SparkContext context = spark.sparkContext();
context.conf().set("spark.mongodb.input.uri","mongodb://host:ip/database.collection");
JavaSparkContext jsc = new JavaSparkContext(context);

从多个MongoDB读取以形成数据集

2 个答案: