pyspark-mongodb collection read command won't execute - mongodb

Question

I have following versions installed :-
spark 2.1.0,
scala 2.11.6,
mongoDB 3.2.17
I tried to start the pyspark shell with following command
./bin/pyspark --packages org.mongodb.spark:mongo-spark-connector_2.11:2.2.0
after this i started spark session as follows
from pyspark.sql import SparkSession
my_spark = SparkSession.builder.appName("myApp").config("spark.mongodb.input.uri", "mongodb://127.0.0.1/mycollection.dummy").config("spark.mongodb.output.uri", "mongodb://127.0.0.1/mycollection.dummy").getOrCreate()
i performed writing to a collection in mongodb db and it is getting executed successfully
but, when i try to read the collection using the command
df = my_spark.read.format("com.mongodb.spark.sql.DefaultSource").option("uri","mongodb://127.0.0.1/mycollection.dummy").load()
it is showing error as follows
17/10/13 10:43:33 ERROR executor.Executor: Exception in task 0.0 in stage 2.0 (TID 2)
java.lang.NoSuchMethodError: org.apache.spark.sql.catalyst.analysis.TypeCoercion$.findTightestCommonType()Lscala/Function2;
at com.mongodb.spark.sql.MongoInferSchema$.com$mongodb$spark$sql$MongoInferSchema$$compatibleType(MongoInferSchema.scala:135)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$3.apply(MongoInferSchema.scala:78)
at com.mongodb.spark.sql.MongoInferSchema$$anonfun$3.apply(MongoInferSchema.scala:78)
at scala.collection.TraversableOnce$$anonfun$foldLeft$1.apply(TraversableOnce.scala:157)
at scala.collection.TraversableOnce$$anonfun$foldLeft$1.apply(TraversableOnce.scala:157)
at scala.collection.Iterator$class.foreach(Iterator.scala:893)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
at scala.collection.TraversableOnce$class.foldLeft(TraversableOnce.scala:157)
at scala.collection.AbstractIterator.foldLeft(Iterator.scala:1336)
at scala.collection.TraversableOnce$class.aggregate(TraversableOnce.scala:214)
at scala.collection.AbstractIterator.aggregate(Iterator.scala:1336)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$24.apply(RDD.scala:1135)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$24.apply(RDD.scala:1135)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$25.apply(RDD.scala:1136)
at org.apache.spark.rdd.RDD$$anonfun$treeAggregate$1$$anonfun$25.apply(RDD.scala:1136)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitions$1$$anonfun$apply$23.apply(RDD.scala:796)
at org.apache.spark.rdd.RDD$$anonfun$mapPartitions$1$$anonfun$apply$23.apply(RDD.scala:796)
at org.apache.spark.rdd.MapPartitionsRDD.compute(MapPartitionsRDD.scala:38)
at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:323)
at org.apache.spark.rdd.RDD.iterator(RDD.scala:287)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
at org.apache.spark.scheduler.Task.run(Task.scala:99)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:282)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)

Answer 1

You seem to have an inconsistency in the dataframe reading line. First of all, you initialize my_spark, but then use spark. You also use "uri", instead of "spark.mongodb.input.uri". Try this below:
df = my_spark.read.format("com.mongodb.spark.sql.DefaultSource").option("spark.mongodb.input.uri","mongodb://127.0.0.1/mycollection.dummy").load()
Otherwise provide more code to check as a whole.