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From "sivaram (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-5820) Unable to process mongodb gridfs collection data in Hadoop Mapreduce
Date Fri, 04 Apr 2014 13:21:14 GMT
sivaram created MAPREDUCE-5820:

             Summary: Unable to process mongodb gridfs collection data in Hadoop Mapreduce
                 Key: MAPREDUCE-5820
                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5820
             Project: Hadoop Map/Reduce
          Issue Type: Bug
          Components: task
    Affects Versions: 2.2.0
         Environment: Hadoop, Mongodb
            Reporter: sivaram

I saved a 2GB pdf file into MongoDB using GridFS. now i want process those GridFS collection
data using Java Spark Mapreduce. previously i have succesfully processed mongoDB collections
with Hadoop mapreduce using Mongo-Hadoop connector. now i'm unable to handle binary data which
is coming from input GridFS collections.

 MongoConfigUtil.setInputURI(config, "mongodb://localhost:27017/pdfbooks.fs.chunks" );
 MongoConfigUtil.setOutputURI(config,"mongodb://localhost:27017/"+output );
 JavaPairRDD<Object, BSONObject> mongoRDD = sc.newAPIHadoopRDD(config,
            com.mongodb.hadoop.MongoInputFormat.class, Object.class,
 JavaRDD<String> words = mongoRDD.flatMap(new FlatMapFunction<Tuple2<Object,BSONObject>,
   String>() {                                
   public Iterable<String> call(Tuple2<Object, BSONObject> arg) {   
In the above code i'm accesing fs.chunks collection as input to my mapper. so mapper is taking
it as BsonObject. but the problem is that input BSONObject data is in unreadable binary format.
for example the above program "System.out.println(arg._2.toString());" statement giving following

   { "_id" : { "$oid" : "533e53048f0c8bcb0b3a7ff7"} , "files_id" : { "$oid" : "533e5303fac7a2e2c4afea08"}
, "n" : 0 , "data" : <Binary Data>}

How Do i print/access that data in readable format. Can i use GridFS Api to do that. if so
please suggest me how to convert input BSONObject to GridFS object and other best ways to
do...Thank you in Advance!!!

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