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Read from MongoDB
This version of the documentation is archived and no longer supported. See the current documentation for the latest version of the MongoDB Connector for Spark.
Pass a JavaSparkContext to MongoSpark.load() to read from
MongoDB into a JavaMongoRDD. The following example loads the data
from the myCollection collection in the test database that was
saved as part of the write example.
package com.mongodb.spark_examples; import org.apache.spark.api.java.JavaSparkContext; import org.apache.spark.sql.SparkSession; import org.bson.Document; import com.mongodb.spark.MongoSpark; import com.mongodb.spark.rdd.api.java.JavaMongoRDD; public final class ReadFromMongoDB { public static void main(final String[] args) throws InterruptedException { SparkSession spark = SparkSession.builder() .master("local") .appName("MongoSparkConnectorIntro") .config("spark.mongodb.input.uri", "mongodb://127.0.0.1/test.myCollection") .config("spark.mongodb.output.uri", "mongodb://127.0.0.1/test.myCollection") .getOrCreate(); // Create a JavaSparkContext using the SparkSession's SparkContext object JavaSparkContext jsc = new JavaSparkContext(spark.sparkContext()); /*Start Example: Read data from MongoDB************************/ JavaMongoRDD<Document> rdd = MongoSpark.load(jsc); /*End Example**************************************************/ // Analyze data from MongoDB System.out.println(rdd.count()); System.out.println(rdd.first().toJson()); jsc.close(); } }
Specify a ReadConfig
MongoSpark.load() can accept a ReadConfig object which
specifies various read configuration settings, such as the collection or the
Read Preference.
The following example reads from the spark collection with a
secondaryPreferred read preference:
package com.mongodb.spark_examples; import java.util.HashMap; import java.util.Map; import org.apache.spark.api.java.JavaSparkContext; import org.apache.spark.sql.SparkSession; import org.bson.Document; import com.mongodb.spark.MongoSpark; import com.mongodb.spark.config.ReadConfig; import com.mongodb.spark.rdd.api.java.JavaMongoRDD; public final class ReadFromMongoDBReadConfig { public static void main(final String[] args) throws InterruptedException { SparkSession spark = SparkSession.builder() .master("local") .appName("MongoSparkConnectorIntro") .config("spark.mongodb.input.uri", "mongodb://127.0.0.1/test.myCollection") .config("spark.mongodb.output.uri", "mongodb://127.0.0.1/test.myCollection") .getOrCreate(); // Create a JavaSparkContext using the SparkSession's SparkContext object JavaSparkContext jsc = new JavaSparkContext(spark.sparkContext()); /*Start Example: Read data from MongoDB************************/ // Create a custom ReadConfig Map<String, String> readOverrides = new HashMap<String, String>(); readOverrides.put("collection", "spark"); readOverrides.put("readPreference.name", "secondaryPreferred"); ReadConfig readConfig = ReadConfig.create(jsc).withOptions(readOverrides); // Load data using the custom ReadConfig JavaMongoRDD<Document> customRdd = MongoSpark.load(jsc, readConfig); /*End Example**************************************************/ // Analyze data from MongoDB System.out.println(customRdd.count()); System.out.println(customRdd.first().toJson()); jsc.close(); } }