Hadoop - MongoDB Webinar June 2014


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Hadoop - MongoDB Webinar June 2014

  1. 1. Mongo-Hadoop Integration Justin Lee Software Engineer @ MongoDB
  2. 2. We will cover: •what it is •how it works •a tour of what it can do A quick briefing on what Mongo and Hadoop are all about: (Q+A at the end)
  3. 3. document-oriented database with dynamic schema stores data in JSON-like documents: { _id : “kosmo kramer”, age : 42, location : { state : ”NY”, zip : ”10024” }, favorite_colors : [“red”, “green”] } different structure in each document values can be simple like strings and ints or nested documents
  4. 4. mongodb scales horizontally via sharding to handle lots of data and load app
  5. 5. Java-based framework for MapReduce Excels at batch processing on large data sets by taking advantage of parallelism map reduce created by google (white paper) implemented in open source by hadoop
  6. 6. Mongo-Hadoop Connector - Why Lots of people using Hadoop and Mongo separately but need integration Custom import/export scripts often used to get data in+out Scalability and flexibility with changes in Hadoop or MongoDB configurations Need to process data across multiple sources custom scripts slow, fragile
  7. 7. Mongo-Hadoop Connector Turn MongoDB into a Hadoop-enabled filesystem: use as the input or output for Hadoop .BSON -or- input data .BSON -or- Hadoop Cluster output results bson file new in 1.1 bson is the output of mongodump
  8. 8. Mongo-Hadoop Connector Benefits + Features Takes advantage of full multi-core parallelism to process data in Mongo Full integration with Hadoop and JVM ecosystems Can be used with Amazon Elastic MapReduce Can read and write backup files from local filesystem, HDFS, or S3
  9. 9. Mongo-Hadoop Connector Vanilla Java MapReduce write MapReduce code in ruby or if you don’t want to use Java, support for Hadoop Streaming. Benefits + Features can write your own language binding
  10. 10. Mongo-Hadoop Connector Support for Pig high-level scripting language for data analysis and building MapReduce workflows Support for Hive SQL-like language for ad-hoc queries + analysis of data sets on Hadoop-compatible file systems Benefits + Features
  11. 11. Mongo-Hadoop Connector How it works: Adapter examines the MongoDB input collection and calculates a set of splits from the data Each split gets assigned to a node in Hadoop cluster In parallel, Hadoop nodes pull data for splits from MongoDB (or BSON) and process them locally Hadoop merges results and streams output back to MongoDB or BSON
  12. 12. Tour of Mongo-Hadoop, by Example - Using Java MapReduce with Mongo-Hadoop - Using Hadoop Streaming - Pig and Hive with Mongo-Hadoop - Elastic MapReduce + BSON
  13. 13. { "_id" : ObjectId("4f2ad4c4d1e2d3f15a000000"), "body" : "Here is our forecastnn ", "filename" : "1.", "headers" : { "From" : "phillip.allen@enron.com", "Subject" : "Forecast Info", "X-bcc" : "", "To" : "tim.belden@enron.com", "X-Origin" : "Allen-P", "X-From" : "Phillip K Allen", "Date" : "Mon, 14 May 2001 16:39:00 -0700 (PDT)", "X-To" : "Tim Belden ", "Message-ID" : "<18782981.1075855378110.JavaMail.evans@thyme>", "Content-Type" : "text/plain; charset=us-ascii", "Mime-Version" : "1.0" } } Input Data: Enron e-mail corpus (501k records, 1.75Gb) each document is one email sender recipients
  14. 14. {"_id": {"t":"bob@enron.com", "f":"alice@enron.com"}, "count" : 14} {"_id": {"t":"bob@enron.com", "f":"eve@enron.com"}, "count" : 9} {"_id": {"t":"alice@enron.com", "f":"charlie@enron.com"}, "count" : 99} {"_id": {"t":"charlie@enron.com", "f":"bob@enron.com"}, "count" : 48} {"_id": {"t":"eve@enron.com", "f":"charlie@enron.com"}, "count" : 20} Let’s use Hadoop to build a graph of (senders → recipients) and the count of messages exchanged between each pair bob alice eve charlie 14 99 9 48 20 sample, simplified data nodes are people. edges/arrows # of msgs from A to B
  15. 15. Example 1 - Java MapReduce mongodb document passed into Hadoop MapReduce Map phase - each input doc gets passed through a Mapper function @Override public  void  map(NullWritable  key,  BSONObject  val,  final  Context  context){        BSONObject  headers  =  (BSONObject)val.get("headers");        if(headers.containsKey("From")  &&  headers.containsKey("To")){                String  from  =  (String)headers.get("From");                String  to  =  (String)headers.get("To");                String[]  recips  =  to.split(",");                for(int  i=0;i<recips.length;i++){                        String  recip  =  recips[i].trim();                        context.write(new  MailPair(from,  recip),  new  IntWritable(1));                }        } } input value doc from mongo. connector will handle translation into BSONObject for you
  16. 16. output written back to MongoDB Example 1 - Java MapReduce (cont) Reduce phase - outputs of Map are grouped together by key and passed to Reducer the {to, from} key list of all the values collected under the key        public  void  reduce(  final  MailPair  pKey,                                                final  Iterable<IntWritable>  pValues,                                                final  Context  pContext  ){                int  sum  =  0;                for  (  final  IntWritable  value  :  pValues  ){                        sum  +=  value.get();                }                BSONObject  outDoc  =  new  BasicDBObjectBuilder().start()                                                        .add(  "f"  ,  pKey.from)                            .add(  "t"  ,  pKey.to  )                            .get();                BSONWritable  pkeyOut  =  new  BSONWritable(outDoc);                pContext.write(  pkeyOut,  new  IntWritable(sum)  );        }
  17. 17. Example 1 - Java MapReduce (cont) mongo.job.input.format=com.mongodb.hadoop.MongoInputFormat mongo.input.uri=mongodb://my-db:27017/enron.messages Read from MongoDB Read from BSON mongo.job.input.format=com.mongodb.hadoop.BSONFileInputFormat mapred.input.dir=file:///tmp/messages.bson hdfs:///tmp/messages.bson s3:///tmp/messages.bson
  18. 18. Example 1 - Java MapReduce (cont) mongo.job.output.format=com.mongodb.hadoop.MongoOutputFormat mongo.output.uri=mongodb://my-db:27017/enron.results_out Write output to MongoDB Write output to BSON mongo.job.output.format=com.mongodb.hadoop.BSONFileOutputFormat mapred.output.dir=file:///tmp/results.bson hdfs:///tmp/results.bson s3:///tmp/results.bson
  19. 19. Results : Output Data mongos> db.results_out.find({"_id.t": /^kenneth.lay/}) { "_id" : { "t" : "kenneth.lay@enron.com", "f" : "15126-1267@m2.innovyx.com" }, "count" : 1 } { "_id" : { "t" : "kenneth.lay@enron.com", "f" : "2586207@www4.imakenews.com" }, "count" : 1 } { "_id" : { "t" : "kenneth.lay@enron.com", "f" : "40enron@enron.com" }, "count" : 2 } { "_id" : { "t" : "kenneth.lay@enron.com", "f" : "a..davis@enron.com" }, "count" : 2 } { "_id" : { "t" : "kenneth.lay@enron.com", "f" : "a..hughes@enron.com" }, "count" : 4 } { "_id" : { "t" : "kenneth.lay@enron.com", "f" : "a..lindholm@enron.com" }, "count" : 1 } { "_id" : { "t" : "kenneth.lay@enron.com", "f" : "a..schroeder@enron.com" }, "count" : 1 } ... has more
  20. 20. Example 2 - Hadoop Streaming Let’s do the same Enron MapReduce job with Python instead of Java $ pip install pymongo_hadoop
  21. 21. Example 2 - Hadoop Streaming (cont) Hadoop passes data to an external process via STDOUT/STDIN map(k, v) map(k, v) map(k, v)map() JVM STDIN Python / Ruby / JS interpreter STDOUT Hadoop (JVM) def mapper(documents): . . .
  22. 22. Example 2 - Hadoop Streaming (cont) from pymongo_hadoop import BSONMapper def mapper(documents): i = 0 for doc in documents: i = i + 1 from_field = doc['headers']['From'] to_field = doc['headers']['To'] recips = [x.strip() for x in to_field.split(',')] for r in recips: yield {'_id': {'f':from_field, 't':r}, 'count': 1} BSONMapper(mapper) print >> sys.stderr, "Done Mapping." BSONMapper is pymongo layer that translates from hadoop streaming back to hadoop
  23. 23. Example 2 - Hadoop Streaming (cont) from pymongo_hadoop import BSONReducer def reducer(key, values): print >> sys.stderr, "Processing from/to %s" % str(key) _count = 0 for v in values: _count += v['count'] return {'_id': key, 'count': _count} BSONReducer(reducer)
  24. 24. Surviving Hadoop: making MapReduce easier Pig + Hive writing m/r jobs from scratch can be clunky and cumbersome
  25. 25. Example 3 - Mongo-Hadoop and Pig Let’s do the same thing yet again, but this time using Pig Pig is a powerful language that can generate sophisticated MapReduce workflows from simple scripts Can perform JOIN, GROUP, and execute user-defined functions (UDFs)
  26. 26. Example 3 - Mongo-Hadoop and Pig (cont) Pig directives for loading data: BSONLoader and MongoLoader Writing data out BSONStorage and MongoInsertStorage data = LOAD 'mongodb://localhost:27017/db.collection' using com.mongodb.hadoop.pig.MongoLoader; STORE records INTO 'file:///output.bson' using com.mongodb.hadoop.pig.BSONStorage;
  27. 27. Pig has its own special datatypes: Bags, Maps, and Tuples Mongo-Hadoop Connector intelligently converts between Pig datatypes and MongoDB datatypes Example 3 - Mongo-Hadoop and Pig (cont) bags -> arrays maps -> objects
  28. 28. raw = LOAD 'hdfs:///messages.bson' using com.mongodb.hadoop.pig.BSONLoader('','headers:[]') ; send_recip = FOREACH raw GENERATE $0#'From' as from, $0#'To' as to; send_recip_filtered = FILTER send_recip BY to IS NOT NULL; send_recip_split = FOREACH send_recip_filtered GENERATE from as from, TRIM(FLATTEN(TOKENIZE(to))) as to; send_recip_grouped = GROUP send_recip_split BY (from, to); send_recip_counted = FOREACH send_recip_grouped GENERATE group, COUNT($1) as count; STORE send_recip_counted INTO 'file:///enron_results.bson' using com.mongodb.hadoop.pig.BSONStorage; Example 3 - Mongo-Hadoop and Pig (cont)
  29. 29. Hive with Mongo-Hadoop Similar idea to Pig - process your data without needing to write MapReduce code from scratch ...but with SQL as the language of choice
  30. 30. Hive with Mongo-Hadoop Sample Data: db.users db.users.find() { "_id": 1, "name": "Tom", "age": 28 } { "_id": 2, "name": "Alice", "age": 18 } { "_id": 3, "name": "Bob", "age": 29 } { "_id": 101, "name": "Scott", "age": 10 } { "_id": 104, "name": "Jesse", "age": 52 } { "_id": 110, "name": "Mike", "age": 32 } ... CREATE TABLE mongo_users (id int, name string, age int) STORED BY "com.mongodb.hadoop.hive.MongoStorageHandler" WITH SERDEPROPERTIES( "mongo.columns.mapping" = "_id,name,age" ) TBLPROPERTIES ( "mongo.uri" = "mongodb://localhost:27017/test.users"); first, declare the collection to be accessible in Hive:
  31. 31. Hive with Mongo-Hadoop ...then you can run SQL on it, like a table. SELECT name,age FROM mongo_users WHERE id > 100 ; SELECT * FROM mongo_users GROUP BY age WHERE id > 100 ; you can use GROUP BY: or JOIN multiple tables/collections together: SELECT * FROM mongo_users T1 JOIN user_emails T2 WHERE T1.id = T2.id; subset of SQL
  32. 32. Write the output of queries back into new tables: INSERT OVERWRITE TABLE old_users SELECT id,name,age FROM mongo_users WHERE age > 100 ; DROP TABLE mongo_users; Drop a table in Hive to delete the underlying collection in MongoDB use “external” when declaring your table to prevent the collection drop
  33. 33. Usage with Amazon Elastic MapReduce Run mongo-hadoop jobs without needing to set up or manage your own Hadoop cluster. Pig, Hive, and streaming work on EMR, too! Logs get captured into S3 files
  34. 34. Usage with Amazon Elastic MapReduce First, make a “bootstrap” script that fetches dependencies (mongo-hadoop jar and java drivers) #!/bin/sh wget -P /home/hadoop/lib http://central.maven.org/maven2/org/ mongodb/mongo-java-driver/2.12.2/mongo-java-driver-2.12.2.jar wget -P /home/hadoop/lib https://s3.amazonaws.com/mongo-hadoop- code/mongo-hadoop-core_1.1.2-1.1.0.jar this will get executed on each node in the cluster that EMR builds for us. working on updating hadoop artifacts in maven
  35. 35. Example 4 - Usage with Amazon Elastic MapReduce Put the bootstrap script, and all your code, into an S3 bucket where Amazon can see it. s3cp ./bootstrap.sh s3://$S3_BUCKET/bootstrap.sh s3mod s3://$S3_BUCKET/bootstrap.sh public-read s3cp $HERE/../enron/target/enron-example.jar s3://$S3_BUCKET/ enron-example.jar s3mod s3://$S3_BUCKET/enron-example.jar public-read
  36. 36. $ elastic-mapreduce --create --jobflow ENRON000 --instance-type m1.xlarge --num-instances 5 --bootstrap-action s3://$S3_BUCKET/bootstrap.sh --log-uri s3://$S3_BUCKET/enron_logs --jar s3://$S3_BUCKET/enron-example.jar --arg -D --arg mongo.job.input.format=com.mongodb.hadoop.BSONFileInputFormat --arg -D --arg mapred.input.dir=s3n://mongo-test-data/messages.bson --arg -D --arg mapred.output.dir=s3n://$S3_BUCKET/BSON_OUT --arg -D --arg mongo.job.output.format=com.mongodb.hadoop.BSONFileOutputFormat # (any additional parameters here) Example 4 - Usage with Amazon Elastic MapReduce ...then launch the job from the command line, pointing to your S3 locations Control the type and number of instances in the cluster
  37. 37. Example 4 - Usage with Amazon Elastic MapReduce Easy to kick off a Hadoop job, without needing to manage a Hadoop cluster Pig, Hive, and streaming work on EMR, too! Logs get captured into S3 files
  38. 38. Example 5 - New Feature: MongoUpdateWritable ... but we can also modify an existing output collection Works by applying mongodb update modifiers: $push, $pull, $addToSet, $inc, $set, etc. Can be used to do incremental MapReduce or “join” two collections In previous examples, we wrote job output data by inserting into a new collection
  39. 39. Example 5 - MongoUpdateWritable For example, let’s say we have two collections. {    "_id":  ObjectId("51b792d381c3e67b0a18d678"),    "sensor_id":  ObjectId("51b792d381c3e67b0a18d4a1"),    "value":  3328.5895416489802,    "timestamp":  ISODate("2013-­‐05-­‐18T13:11:38.709-­‐0400"),    "loc":  [-­‐175.13,51.658] } {    "_id":  ObjectId("51b792d381c3e67b0a18d0ed"),    "name":  "730LsRkX",    "type":  "pressure",    "owner":  "steve", } sensors log events refers to which sensor logged the event For each owner, we want to calculate how many events were recorded for each type of sensor that logged it.
  40. 40. For each owner, we want to calculate how many events were recorded for each type of sensor that logged it. Plain english: Bob’s sensors for temperature have stored 1300 readings Bob’s sensors for pressure have stored 400 readings Alice’s sensors for humidity have stored 600 readings Alice’s sensors for temperature have stored 700 readings etc...
  41. 41. sensors (mongodb collection) Stage 1 -MapReduce on sensors collection Results (mongodb collection) for each sensor, emit: {key: owner+type, value: _id} group data from map() under each key, output: {key: owner+type, val: [ list of _ids] } read from mongodb insert() new records to mongodb MapReduce log events (mongodb collection) do this in two stages
  42. 42. the sensor’s owner and type After stage one, the output docs look like: list of ID’s of sensors with this owner and type {    "_id":  "alice  pressure",    "sensors":  [        ObjectId("51b792d381c3e67b0a18d475"),        ObjectId("51b792d381c3e67b0a18d16d"),        ObjectId("51b792d381c3e67b0a18d2bf"),        …    ] } Now we just need to count the total # of log events recorded for any sensors that appear in the list for each owner/type group.
  43. 43. sensors (mongodb collection) Stage 2 -MapReduce on log events collection read from mongodb Results (mongodb collection) update() existing records in mongodb MapReduce log events (mongodb collection) for each sensor, emit: {key: sensor_id, value: 1} group data from map() under each key for each value in that key: update({sensors: key}, {$inc : {logs_count:1}}) context.write(null,   new  MongoUpdateWritable(      query,  //which  documents  to  modify        update,  //how  to  modify  ($inc)      true,        //upsert      false) );  //  multi
  44. 44. Example - MongoUpdateWritable Result after stage 2 {    "_id":  "1UoTcvnCTz  temp",    "sensors":  [        ObjectId("51b792d381c3e67b0a18d475"),        ObjectId("51b792d381c3e67b0a18d16d"),        ObjectId("51b792d381c3e67b0a18d2bf"),        …    ],    "logs_count":  1050616 } now populated with correct count
  45. 45. New Features in v1.2 and beyond Continually improving Hive support Performance Improvements - Lazy BSON Support for multi-collection input sources API for adding custom splitter implementations and more primarily focusing on hive but pig is next maven central
  46. 46. Recap Mongo-Hadoop - use Hadoop to do massive computations on big data sets stored in MongoDB/BSON Tools and APIs make it easier: Streaming, Pig, Hive, EMR, etc. MongoDB becomes a Hadoop-enabled filesystem
  47. 47. Questions? https://github.com/mongodb/mongo-hadoop/tree/ master/examples Examples can be found on github:
  48. 48. MongoDB World New York City, June 23-25 Save 25% with 25JustinLee Register at world.mongodb.com