Introduction to Apache Accumulo
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Presented at the Boulder/Denver BigData Meetup on March 21, 2012
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Introduction to Apache Accumulo
- 1. Introduction to Apache Accumulo Boulder/Denver BigData Meetup - March 21,2012 Jared Winick @jaredwinick
- 2. Accumulo /əˈkjuˈmj ʊ/ ʊˈlo 1. Sorted, distributed key/value store with cell-based access control and customizable server-side processing
- 4. Annotation Added Jeff Dean: Designs, Lessons and Advice from Building Large Distributed Systems http://www.cs.cornell.edu/projects/ladis2009/talks/dean-keynote-ladis2009.pdf
- 5. Enables interactive access to… Trillions of records petabytes of indexed data across 100s-1000s of servers
- 6. Short Accumulo History Lesson http://www.flickr.com/photos/mr_t_in_dc/4249886990/sizes/l/in/photostream/
- 7. 2006
- 9. 2011
- 10. 2012
- 11. Uses of BigTable and Kin (BigTable) (HBase) •Google Analytics1 •Messages3,4,6 •Crawl1 •Insights5,6 •AppEngine Datastore2 •Many more1 (Cassandra) (Accumulo) •Rainbird (realtime analytics)7 •??? 1.) http://static.googleusercontent.com/external_content/untrusted_dlcp/research.google.com/en/us/archive/bigtable-osdi06.pdf 2.) http://code.google.com/appengine/articles/storage_breakdown.html 3.) http://www.facebook.com/note.php?note_id=454991608919 4.) http://mvdirona.com/jrh/TalksAndPapers/KannanMuthukkaruppan_StorageInfraBehindMessages.pdf 5.) http://www.facebook.com/note.php?note_id=10150103900258920 6.) http://borthakur.com/ftp/SIGMODRealtimeHadoopPresentation.pdf 7.) http://www.slideshare.net/kevinweil/rainbird-realtime-analytics-at-twitter-strata-2011
- 12. Accumulo /əˈkjuˈmj ʊ/ ʊˈlo 1. Sorted, distributed key/value store with cell-based access control and customizable server-side processing
- 13. Multi-dimension Key Key Column Value Row ID Timestamp Family Qualifier Visibility http://incubator.apache.org/accumulo/user_manual_1.4-incubating/Accumulo_Design.html
- 14. Keys Sorted Lexicographically Row ID, Column Family, Column Qualifier, Column Visibility, Timestamp Everything is a byte[] except the Timestamp which is a long
- 15. Physical Layout Key Value Row ID Col Fam Col Qual Col Vis Time Value Alice properties age public March 2011 31 Alice properties phone private Feb 2011 555-1234 Alice purchases Xbox public Feb 2011 $299 Bob properties phone private March 2011 555-4321 Bob purchases iPhone Public Feb 2011 $399
- 16. Queries •By exact Key or range of Keys •Data is always returned in sorted order Query Requirements Drive Data Model Design
- 18. Hadoop Clients MapReduce Read/ Analytics Write Accumulo Configuration/ Storage State Hadoop HDFS Zookeeper
- 19. Table Tablets Accumulo … Tablet Server … … Tablet Server … ... … Tablet Server … Master Data Node Data Node ... Data Node Name Node Hadoop HDFS
- 20. Table Tablet Server Failure Tablets 1.) Detect Failure Accumulo Tablet Server Tablet Server ... Tablet Server Master 2.) Reassign Data Node Data Node ... Data Node Name Node Hadoop HDFS
- 21. Writes Write- Ahead Accumulo Log (WAL) Tablet Server 1 Tablet 2 MemTable Client Data Node ... Data Node Data Node Hadoop HDFS
- 22. Writes Write- Ahead Accumulo Log (WAL) Tablet Server 1 Tablet 2 MemTable Client 3 File 1 Data Node ... Data Node Data Node Hadoop HDFS
- 23. Compactions Minor Major The process of flushing The process of a MemTable of a Tablet combining multiple files to a single file in HDFS into a single file
- 24. Tablet Splits • Tablets are split when they reach a max size • Always split on row boundary • Master assigns a split Tablet to another Tablet server (no data is moved!)
- 25. Reads Accumulo Tablet Server Tablet MemTable Client File 1 File 1
- 26. Accumulo /əˈkjuˈmj ʊ/ ʊˈlo 1. Sorted, distributed key/value store with cell-based access control and customizable server-side processing
- 28. Iterators Can be run at: Can do things like: •Scan Time •Aggregation (Combiners) •Minor Compaction •Age-Off •Major Compaction •Filtering (access control) •Transformation Push Processing to the Data
- 29. Accumulo /əˈkjuˈmj ʊ/ ʊˈlo 1. Sorted, distributed key/value store with cell-based access control and customizable server-side processing
- 30. Access Control • Every key-value has a visibility label • Label is defined with boolean operators • Label is arbitrary and ad-hoc Public Private | Admin Finance | (HR & Manager) • Authorizations presented at scan time • Data is filtered out automatically by system- level Iterator
- 31. Access Control – Typical Architecture Trusted Zone 6.) Return Data 5.) Return Visible Data Web Server Accumulo 1.) Pass Credentials 4.) Proxy Authorization 3.) Return Authorizations 2.) Lookup User Enterprise Identity Management
- 32. Access Control – Typical Architecture Trusted Zone Accumulo 6.) Return [6,8] 5.) Return [6,8] SECRET&PROJECT X, 6 Web Server SECRET&PROJECT Y, 8 1.) PKI Cert 4.) Proxy Bob’s Auths SECRET&PROJECT Z, 3 Bob 3.) Auths:[SECRET, UNCLASSIFIED, 2.) Lookup PROJECT X, PROJECT Y] Bob Enterprise Identity Management
- 33. Demo
- 34. Application Requirements Build an application to analyze trends in Twitter messages. •Query for word/phrase and view real-time activity in a time series graph •View at different time ranges (1 day, 7 days, 30 days, etc) •Allow multiple query terms to compare activity (ex. Breakfast,Lunch) •Automatically extract daily trends for the user
- 35. Demo Setup/Data • Twitter Streaming API • US country codes only messages • 1,2,3-grams built • Data since Dec 24 – Live • Running on average workstation, 1 SATA disk, 6 GB memory. • 72GB, 2.6 billion entries and counting
- 37. Data Model • Tweets table – Row ID: n-gram – Column Family: Date Granularity (DAY, HOUR) – Column Qual: Date Value – Value: Count – SummingCombiner (Iterator) used to update Count Row ID Col Fam Col Qual Value breakfast DAY 20120318 31 breakfast DAY 20120319 56 … … … … lunch HOUR 2012031801 3 lunch HOUR 2012031802 4
- 38. Data Model • Trends table – Row ID: (Date Granularity + Date Value) – Column Family: (Integer.MAX_VALUE – trendScore) – Column Qual: n-gram – Value: [] Row ID Col Fam Col Qual Value DAY:20120318 2147483145 church DAY:20120318 2147483316 hangover … … … … DAY:20120319 2147476521 the broncos DAY:20120319 2147477704 tim tebow
- 39. MapReduce Analytics • Utilize MapReduce for building trends • AccumuloInputFormat reads from tweets table • AccumuloOutputFormat writes to trends table • AccumuloStorage LoadFunc for Pig available on github
- 41. Summary •Accumulo exploits locality to enable interactive access to huge data sets while adding cell-level access control and server- side programming •Nothing in life is free. Accumulo comes with the complexity and responsibility of managing a distributed system and designing indexes on your data
- 42. References • Documentation, Mailing Lists, Links http://incubator.apache.org/accumulo/ • HBase Shootout http://www.slideshare.net/cloudera/h-base-and-accumulo-todd-lipcom-jan-25-2012 • Trendulo https://github.com/jaredwinick/trendulo
Hinweis der Redaktion
- Obviously most people’s data set isn’t this large. If you can fit your data into memory of a single large server, Accumulo probably isn’t for you.
- 20 billion events day for Insights6+ billion msg -> 75 billion rw operations/day
- Sparse,sorted
- Table is partitioned into tablets which are logically assigned to tablet servers (they are physically in HDFS). Tablet is a range of keys.
- Tablets are only logically assigned to tablet servers by theAccumulo Master. The are physically stored in HDFS. Tablet is one or more files.
- Data first written to WAL (outside of HDFS on a different machine), then inserted into sorted MemTable (balanced, sorted binary tree)
- When MemTable is full, it gets flushed to a file which is stored in HDFS (minor compaction). Writes to disk are sequential as MemTable is sorted
- All of these files are always sorted!
- TabletServer merges key-values from all its files and its MemTable to present a complete sorted view of data
- One of the most powerful features of Accumulo – a lot to learn. Come back to aggregation in demo
- Example: Trendistic (http://trendistic.indextank.com)
- Documentation is a work in progress…