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Hadoop and Pig @Twitter
              Kevin Weil -- @kevinweil
              Analytics Lead, Twitter




                                         TM




Friday, July 23, 2010
Agenda
           ‣     Hadoop Overview
           ‣     Pig: Rapid Learning Over Big Data
           ‣     Data-Driven Products
           ‣     Hadoop/Pig and Analytics




Friday, July 23, 2010
My Background
           ‣     Mathematics and Physics at Harvard, Physics at
                 Stanford
           ‣     Tropos Networks (city-wide wireless): mesh
                 routing algorithms, GBs of data
           ‣     Cooliris (web media): Hadoop and Pig for
                 analytics, TBs of data
           ‣     Twitter: Hadoop, Pig, HBase, Cassandra,
                 machine learning, visualization, social graph
                 analysis, soon to be PBs data



Friday, July 23, 2010
Agenda
           ‣     Hadoop Overview
           ‣     Pig: Rapid Learning Over Big Data
           ‣     Data-Driven Products
           ‣     Hadoop/Pig and Analytics




Friday, July 23, 2010
Data is Getting Big
           ‣     NYSE: 1 TB/day
           ‣     Facebook: 20+ TB
                 compressed/day
           ‣     CERN/LHC: 40 TB/day
                 (15 PB/year)
           ‣     And growth is
                 accelerating
           ‣     Need multiple machines,
                 horizontal scalability


Friday, July 23, 2010
Hadoop
           ‣      Distributed file system (hard to store a PB)
           ‣      Fault-tolerant, handles replication, node failure,
                  etc
           ‣      MapReduce-based parallel computation
                  (even harder to process a PB)
           ‣      Generic key-value based computation interface
                  allows for wide applicability




Friday, July 23, 2010
Hadoop
           ‣      Open source: top-level Apache project
           ‣      Scalable: Y! has a 4000-node cluster
           ‣      Powerful: sorted a TB of random integers in 62
                  seconds


           ‣      Easy Packaging: Cloudera RPMs, DEBs




Friday, July 23, 2010
MapReduce Workflow
    Inputs
                                                           ‣   Challenge: how many tweets per
                        Map
                              Shuffle/Sort                      user, given tweets table?
                        Map
                                                           ‣   Input: key=row, value=tweet info
                                                 Outputs
                        Map             Reduce             ‣   Map: output key=user_id,
                        Map             Reduce
                                                               value=1
                        Map             Reduce             ‣   Shuffle: sort by user_id
                        Map                                ‣   Reduce: for each user_id, sum
                        Map
                                                           ‣   Output: user_id, tweet count
                                                           ‣   With 2x machines, runs 2x faster

Friday, July 23, 2010
MapReduce Workflow
    Inputs
                                                           ‣   Challenge: how many tweets per
                        Map
                              Shuffle/Sort                      user, given tweets table?
                        Map
                                                           ‣   Input: key=row, value=tweet info
                                                 Outputs
                        Map             Reduce             ‣   Map: output key=user_id,
                        Map             Reduce
                                                               value=1
                        Map             Reduce             ‣   Shuffle: sort by user_id
                        Map                                ‣   Reduce: for each user_id, sum
                        Map
                                                           ‣   Output: user_id, tweet count
                                                           ‣   With 2x machines, runs 2x faster

Friday, July 23, 2010
MapReduce Workflow
    Inputs
                                                           ‣   Challenge: how many tweets per
                        Map
                              Shuffle/Sort                      user, given tweets table?
                        Map
                                                           ‣   Input: key=row, value=tweet info
                                                 Outputs
                        Map             Reduce             ‣   Map: output key=user_id,
                        Map             Reduce
                                                               value=1
                        Map             Reduce             ‣   Shuffle: sort by user_id
                        Map                                ‣   Reduce: for each user_id, sum
                        Map
                                                           ‣   Output: user_id, tweet count
                                                           ‣   With 2x machines, runs 2x faster

Friday, July 23, 2010
MapReduce Workflow
    Inputs
                                                           ‣   Challenge: how many tweets per
                        Map
                              Shuffle/Sort                      user, given tweets table?
                        Map
                                                           ‣   Input: key=row, value=tweet info
                                                 Outputs
                        Map             Reduce             ‣   Map: output key=user_id,
                        Map             Reduce
                                                               value=1
                        Map             Reduce             ‣   Shuffle: sort by user_id
                        Map                                ‣   Reduce: for each user_id, sum
                        Map
                                                           ‣   Output: user_id, tweet count
                                                           ‣   With 2x machines, runs 2x faster

Friday, July 23, 2010
MapReduce Workflow
    Inputs
                                                           ‣   Challenge: how many tweets per
                        Map
                              Shuffle/Sort                      user, given tweets table?
                        Map
                                                           ‣   Input: key=row, value=tweet info
                                                 Outputs
                        Map             Reduce             ‣   Map: output key=user_id,
                        Map             Reduce
                                                               value=1
                        Map             Reduce             ‣   Shuffle: sort by user_id
                        Map                                ‣   Reduce: for each user_id, sum
                        Map
                                                           ‣   Output: user_id, tweet count
                                                           ‣   With 2x machines, runs 2x faster

Friday, July 23, 2010
MapReduce Workflow
    Inputs
                                                           ‣   Challenge: how many tweets per
                        Map
                              Shuffle/Sort                      user, given tweets table?
                        Map
                                                           ‣   Input: key=row, value=tweet info
                                                 Outputs
                        Map             Reduce             ‣   Map: output key=user_id,
                        Map             Reduce
                                                               value=1
                        Map             Reduce             ‣   Shuffle: sort by user_id
                        Map                                ‣   Reduce: for each user_id, sum
                        Map
                                                           ‣   Output: user_id, tweet count
                                                           ‣   With 2x machines, runs 2x faster

Friday, July 23, 2010
MapReduce Workflow
    Inputs
                                                           ‣   Challenge: how many tweets per
                        Map
                              Shuffle/Sort                      user, given tweets table?
                        Map
                                                           ‣   Input: key=row, value=tweet info
                                                 Outputs
                        Map             Reduce             ‣   Map: output key=user_id,
                        Map             Reduce
                                                               value=1
                        Map             Reduce             ‣   Shuffle: sort by user_id
                        Map                                ‣   Reduce: for each user_id, sum
                        Map
                                                           ‣   Output: user_id, tweet count
                                                           ‣   With 2x machines, runs 2x faster

Friday, July 23, 2010
But...
           ‣     Analysis typically in Java
           ‣     Single-input, two-stage
                 data flow is rigid
           ‣     Projections, filters:
                 custom code
           ‣     Joins are lengthy, error-prone
           ‣     Hard to manage n-stage jobs
           ‣     Exploration requires compilation!



Friday, July 23, 2010
Agenda
           ‣     Hadoop Overview
           ‣     Pig: Rapid Learning Over Big Data
           ‣     Data-Driven Products
           ‣     Hadoop/Pig and Analytics




Friday, July 23, 2010
Enter Pig
          ‣      High level language
          ‣      Transformations on
                 sets of records
          ‣      Process data one step at a time
          ‣      Easier than SQL?


          ‣      Top-level Apache project



Friday, July 23, 2010
Why Pig?
             ‣      Because I bet you can read the following script.




Friday, July 23, 2010
A Real Pig Script




Friday, July 23, 2010
Now, just for fun...
             ‣      The same calculation in vanilla MapReduce




Friday, July 23, 2010
No, seriously.




Friday, July 23, 2010
Pig Democratizes Large-scale
           Data Analysis
           ‣     The Pig version is:
           ‣            5% of the code
           ‣            5% of the development time
           ‣            Within 25% of the execution time
           ‣            Readable, reusable




Friday, July 23, 2010
One Thing I’ve Learned
           ‣     It’s easy to answer questions
           ‣     It’s hard to ask the right questions


           ‣     Value the system that promotes innovation and
                 iteration




Friday, July 23, 2010
Agenda
           ‣     Hadoop Overview
           ‣     Pig: Rapid Learning Over Big Data
           ‣     Data-Driven Products
           ‣     Hadoop/Pig and Analytics




Friday, July 23, 2010
MySQL, MySQL, MySQL
           ‣     We all start there.
           ‣     But MySQL is not built for analysis.
           ‣     select count(*) from users? Maybe.
           ‣     select count(*) from tweets? Uh...
           ‣     Imagine joining them.
           ‣     And grouping.
           ‣     Then sorting.



Friday, July 23, 2010
Non-Pig Hadoop at Twitter
           ‣     Data Sink via Scribe
           ‣     Distributed Grep
           ‣     A few performance-critical, simple jobs
           ‣     People Search




Friday, July 23, 2010
People Search?
           ‣     First real product built with Hadoop
           ‣     “Find People”
           ‣     Old version: offline process on
                 a single node
           ‣     New version: complex graph
                 calculations, hit internal network
                 services, custom indexing
           ‣     	      Faster, more reliable,
                 more observable
Friday, July 23, 2010
People Search
           ‣     Import user data into HBase
           ‣     Periodic MapReduce job reading from HBase
           ‣      Hits FlockDB, other internal services in
                 mapper
           ‣            Custom partitioning
           ‣     Data sucked across to sharded, replicated,
                 horizontally scalable, in-memory, low-latency
                 Scala service
           ‣       Build a trie, do case folding/normalization,
                 suggestions, etc
Friday, July 23, 2010
Agenda
           ‣     Hadoop Overview
           ‣     Pig: Rapid Learning Over Big Data
           ‣     Data-Driven Products
           ‣     Hadoop/Pig and Analytics




Friday, July 23, 2010
Order of Operations

          ‣      Counting



          ‣      Correlating



          ‣      Research/
                 Algorithmic
                 Learning

Friday, July 23, 2010
Counting
           ‣     How many requests per day?
           ‣     What’s the average latency? 95% latency?
           ‣     What’s the response code distribution?
           ‣     How many searches per day? Unique users?
           ‣     What’s the geographic breakdown of requests?
           ‣     How many tweets? From what clients?
           ‣     How many signups? Profile completeness?
           ‣     How many SMS notifications did we send?


Friday, July 23, 2010
Correlating
           ‣     How does usage differ for mobile users?
           ‣     ... for desktop client users (Tweetdeck, etc)?
           ‣     Cohort analyses
           ‣     What services fail at the same time?
           ‣     What features get users hooked?
           ‣     What do successful users do often?
           ‣     How does tweet volume change over time?



Friday, July 23, 2010
Research
           ‣     What can we infer from a user’s tweets?
           ‣     ... from the tweets of their followers? followees?
           ‣     What features tend to get a tweet retweeted?
           ‣     ... and what influences the retweet tree depth?
           ‣     Duplicate detection, language detection
           ‣     What graph structures lead to increased usage?
           ‣     Sentiment analysis, entity extraction
           ‣     User reputation


Friday, July 23, 2010
If We Had More Time...
           ‣     HBase
           ‣     LZO compression and Hadoop
           ‣     Protocol buffers
           ‣     Our open source: hadoop-lzo, elephant-bird
           ‣     Analytics and Cassandra




Friday, July 23, 2010
Questions?
                   Follow me at
                   twitter.com/kevinweil



                                           TM




Friday, July 23, 2010

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Hadoop and pig at twitter (oscon 2010)

  • 1. Hadoop and Pig @Twitter Kevin Weil -- @kevinweil Analytics Lead, Twitter TM Friday, July 23, 2010
  • 2. Agenda ‣ Hadoop Overview ‣ Pig: Rapid Learning Over Big Data ‣ Data-Driven Products ‣ Hadoop/Pig and Analytics Friday, July 23, 2010
  • 3. My Background ‣ Mathematics and Physics at Harvard, Physics at Stanford ‣ Tropos Networks (city-wide wireless): mesh routing algorithms, GBs of data ‣ Cooliris (web media): Hadoop and Pig for analytics, TBs of data ‣ Twitter: Hadoop, Pig, HBase, Cassandra, machine learning, visualization, social graph analysis, soon to be PBs data Friday, July 23, 2010
  • 4. Agenda ‣ Hadoop Overview ‣ Pig: Rapid Learning Over Big Data ‣ Data-Driven Products ‣ Hadoop/Pig and Analytics Friday, July 23, 2010
  • 5. Data is Getting Big ‣ NYSE: 1 TB/day ‣ Facebook: 20+ TB compressed/day ‣ CERN/LHC: 40 TB/day (15 PB/year) ‣ And growth is accelerating ‣ Need multiple machines, horizontal scalability Friday, July 23, 2010
  • 6. Hadoop ‣ Distributed file system (hard to store a PB) ‣ Fault-tolerant, handles replication, node failure, etc ‣ MapReduce-based parallel computation (even harder to process a PB) ‣ Generic key-value based computation interface allows for wide applicability Friday, July 23, 2010
  • 7. Hadoop ‣ Open source: top-level Apache project ‣ Scalable: Y! has a 4000-node cluster ‣ Powerful: sorted a TB of random integers in 62 seconds ‣ Easy Packaging: Cloudera RPMs, DEBs Friday, July 23, 2010
  • 8. MapReduce Workflow Inputs ‣ Challenge: how many tweets per Map Shuffle/Sort user, given tweets table? Map ‣ Input: key=row, value=tweet info Outputs Map Reduce ‣ Map: output key=user_id, Map Reduce value=1 Map Reduce ‣ Shuffle: sort by user_id Map ‣ Reduce: for each user_id, sum Map ‣ Output: user_id, tweet count ‣ With 2x machines, runs 2x faster Friday, July 23, 2010
  • 9. MapReduce Workflow Inputs ‣ Challenge: how many tweets per Map Shuffle/Sort user, given tweets table? Map ‣ Input: key=row, value=tweet info Outputs Map Reduce ‣ Map: output key=user_id, Map Reduce value=1 Map Reduce ‣ Shuffle: sort by user_id Map ‣ Reduce: for each user_id, sum Map ‣ Output: user_id, tweet count ‣ With 2x machines, runs 2x faster Friday, July 23, 2010
  • 10. MapReduce Workflow Inputs ‣ Challenge: how many tweets per Map Shuffle/Sort user, given tweets table? Map ‣ Input: key=row, value=tweet info Outputs Map Reduce ‣ Map: output key=user_id, Map Reduce value=1 Map Reduce ‣ Shuffle: sort by user_id Map ‣ Reduce: for each user_id, sum Map ‣ Output: user_id, tweet count ‣ With 2x machines, runs 2x faster Friday, July 23, 2010
  • 11. MapReduce Workflow Inputs ‣ Challenge: how many tweets per Map Shuffle/Sort user, given tweets table? Map ‣ Input: key=row, value=tweet info Outputs Map Reduce ‣ Map: output key=user_id, Map Reduce value=1 Map Reduce ‣ Shuffle: sort by user_id Map ‣ Reduce: for each user_id, sum Map ‣ Output: user_id, tweet count ‣ With 2x machines, runs 2x faster Friday, July 23, 2010
  • 12. MapReduce Workflow Inputs ‣ Challenge: how many tweets per Map Shuffle/Sort user, given tweets table? Map ‣ Input: key=row, value=tweet info Outputs Map Reduce ‣ Map: output key=user_id, Map Reduce value=1 Map Reduce ‣ Shuffle: sort by user_id Map ‣ Reduce: for each user_id, sum Map ‣ Output: user_id, tweet count ‣ With 2x machines, runs 2x faster Friday, July 23, 2010
  • 13. MapReduce Workflow Inputs ‣ Challenge: how many tweets per Map Shuffle/Sort user, given tweets table? Map ‣ Input: key=row, value=tweet info Outputs Map Reduce ‣ Map: output key=user_id, Map Reduce value=1 Map Reduce ‣ Shuffle: sort by user_id Map ‣ Reduce: for each user_id, sum Map ‣ Output: user_id, tweet count ‣ With 2x machines, runs 2x faster Friday, July 23, 2010
  • 14. MapReduce Workflow Inputs ‣ Challenge: how many tweets per Map Shuffle/Sort user, given tweets table? Map ‣ Input: key=row, value=tweet info Outputs Map Reduce ‣ Map: output key=user_id, Map Reduce value=1 Map Reduce ‣ Shuffle: sort by user_id Map ‣ Reduce: for each user_id, sum Map ‣ Output: user_id, tweet count ‣ With 2x machines, runs 2x faster Friday, July 23, 2010
  • 15. But... ‣ Analysis typically in Java ‣ Single-input, two-stage data flow is rigid ‣ Projections, filters: custom code ‣ Joins are lengthy, error-prone ‣ Hard to manage n-stage jobs ‣ Exploration requires compilation! Friday, July 23, 2010
  • 16. Agenda ‣ Hadoop Overview ‣ Pig: Rapid Learning Over Big Data ‣ Data-Driven Products ‣ Hadoop/Pig and Analytics Friday, July 23, 2010
  • 17. Enter Pig ‣ High level language ‣ Transformations on sets of records ‣ Process data one step at a time ‣ Easier than SQL? ‣ Top-level Apache project Friday, July 23, 2010
  • 18. Why Pig? ‣ Because I bet you can read the following script. Friday, July 23, 2010
  • 19. A Real Pig Script Friday, July 23, 2010
  • 20. Now, just for fun... ‣ The same calculation in vanilla MapReduce Friday, July 23, 2010
  • 22. Pig Democratizes Large-scale Data Analysis ‣ The Pig version is: ‣ 5% of the code ‣ 5% of the development time ‣ Within 25% of the execution time ‣ Readable, reusable Friday, July 23, 2010
  • 23. One Thing I’ve Learned ‣ It’s easy to answer questions ‣ It’s hard to ask the right questions ‣ Value the system that promotes innovation and iteration Friday, July 23, 2010
  • 24. Agenda ‣ Hadoop Overview ‣ Pig: Rapid Learning Over Big Data ‣ Data-Driven Products ‣ Hadoop/Pig and Analytics Friday, July 23, 2010
  • 25. MySQL, MySQL, MySQL ‣ We all start there. ‣ But MySQL is not built for analysis. ‣ select count(*) from users? Maybe. ‣ select count(*) from tweets? Uh... ‣ Imagine joining them. ‣ And grouping. ‣ Then sorting. Friday, July 23, 2010
  • 26. Non-Pig Hadoop at Twitter ‣ Data Sink via Scribe ‣ Distributed Grep ‣ A few performance-critical, simple jobs ‣ People Search Friday, July 23, 2010
  • 27. People Search? ‣ First real product built with Hadoop ‣ “Find People” ‣ Old version: offline process on a single node ‣ New version: complex graph calculations, hit internal network services, custom indexing ‣ Faster, more reliable, more observable Friday, July 23, 2010
  • 28. People Search ‣ Import user data into HBase ‣ Periodic MapReduce job reading from HBase ‣ Hits FlockDB, other internal services in mapper ‣ Custom partitioning ‣ Data sucked across to sharded, replicated, horizontally scalable, in-memory, low-latency Scala service ‣ Build a trie, do case folding/normalization, suggestions, etc Friday, July 23, 2010
  • 29. Agenda ‣ Hadoop Overview ‣ Pig: Rapid Learning Over Big Data ‣ Data-Driven Products ‣ Hadoop/Pig and Analytics Friday, July 23, 2010
  • 30. Order of Operations ‣ Counting ‣ Correlating ‣ Research/ Algorithmic Learning Friday, July 23, 2010
  • 31. Counting ‣ How many requests per day? ‣ What’s the average latency? 95% latency? ‣ What’s the response code distribution? ‣ How many searches per day? Unique users? ‣ What’s the geographic breakdown of requests? ‣ How many tweets? From what clients? ‣ How many signups? Profile completeness? ‣ How many SMS notifications did we send? Friday, July 23, 2010
  • 32. Correlating ‣ How does usage differ for mobile users? ‣ ... for desktop client users (Tweetdeck, etc)? ‣ Cohort analyses ‣ What services fail at the same time? ‣ What features get users hooked? ‣ What do successful users do often? ‣ How does tweet volume change over time? Friday, July 23, 2010
  • 33. Research ‣ What can we infer from a user’s tweets? ‣ ... from the tweets of their followers? followees? ‣ What features tend to get a tweet retweeted? ‣ ... and what influences the retweet tree depth? ‣ Duplicate detection, language detection ‣ What graph structures lead to increased usage? ‣ Sentiment analysis, entity extraction ‣ User reputation Friday, July 23, 2010
  • 34. If We Had More Time... ‣ HBase ‣ LZO compression and Hadoop ‣ Protocol buffers ‣ Our open source: hadoop-lzo, elephant-bird ‣ Analytics and Cassandra Friday, July 23, 2010
  • 35. Questions? Follow me at twitter.com/kevinweil TM Friday, July 23, 2010