C* Summit 2013: Real World, Real Time Data Modeling by Tim Moreton
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Data modeling for Cassandra presents a new set of challenges, especially for developers with a background in relational data modeling. And there are added complexities in modeling for analytic applications which need to enable statistical functions over the data, but a good data model, exploiting Cassandra's strengths, can make all the difference to a successful project. This tutorial will examine a number of real-world customer data modeling examples and draw out some hints and tips that will benefit hnot just the Cassandra newbie, but also the more experienced data modeler.
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C* Summit 2013: Real World, Real Time Data Modeling by Tim Moreton
- 1. #Cassandra13 Real World, Real-Time Data Modeling (for analytics apps) Tim Moreton Founder and CTO, Acunu
- 2. #Cassandra13 Virtual nodes CQL Support WE C*
- 3. #Cassandra13 •e.g Click stream, telemetry, logs •100x more writes than reads •Almost all reads are to results •Almost no writes are ‘updates’ •Really not going to fit in RAM Real-time analytics 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html •e.g User profiles •Create, Read, Update, Delete •Probably mostly reads •Probably wants atomicity •Probably fits in RAM Session storage 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html What folk use C* for
- 4. #Cassandra13 Real-time analytics 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html Session storage 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html 02:44:02 241.24.41 0.0.1 GET /index.html What folk use C* for S WP HA ACIDS WP HA ACID
- 5. #Cassandra13 Real-time analytics What folk use C* for Session storage
- 6. #Cassandra13 Example use case { time: 13:50:11, latitude: 12.5, longitude: -43.4, duration: 24, device_type: .. } Call detail records tens thousands/sec Real-time dashboards
- 7. #Cassandra13 C* Data Modeling 101 • Denormalise: Writes (and disk) are cheap, reads are expensive: insert data in every arrangement that you need to read it • Items you’ll access together, and want sorted: put in the same row • Sets of items you’re likely to access separately: keep in separate rows • Atomic counters are the building block of Cassandra real-time analytics apps row2 row3 row1 One event update One query read
- 8. #Cassandra13 #1: Hierarchies 13:00 ... :01→45 :02→62 :03→87 <day> ... :12→2930 :13→3520 :14→3034 13:01 ... :10→3 :11→4 :12→2 14:00 13:02 ...... Counting occurrences by day, hour, min, sec One row for each value at each level in the hierarchy Columns encode sub-components for each level
- 9. #Cassandra13 #1: Hierarchies { time: 13:02:11, .... } 13:00 ... :01→45 :02→62 :03→87 <day> ... :12→2930 :13→3520 :14→3034 13:01 ... :10→3 :11→4 :12→2 14:00 13:02 ...... 11:59 -> 13:02 Counting occurrences by day, hour, min, sec
- 10. #Cassandra13 #2: Filtering { time: 13:50:11, device_type : xx, } 13:00 ... :01→45 :02→62 :03→87 xx yy <day> xx yy 13:01 xx yy 14:00 13:02 xx yy ...... Adding ‘WHERE’s To filter on a field, make sure it is in the partition key
- 11. #Cassandra13 #3: Grouping { time: 13:50:11, device_type : xx, } Adding ‘GROUP BY’ 13:00 ... :01, xx→45 :01, yy→3 :02, xx→7 <day> ... :12, xx→1012 :12,yy→542 :13,xx→228 14:00 ......
- 12. #Cassandra13 #4: Drilldown 13:00 ... :01, e3→- :01, e4→- :02, e5→- <day> ... :12, e1→- :12,e2→- :13,e3→- 14:00 ...... Going from counts to the constituent events { _id: e3, time: 13:01:11, device_type : xx, } e3 time → 13:01:11 device_type → xx ... Use an identifier in the column key and store the event in a different ColumnFamily
- 13. #Cassandra13 Put it together... Source: http://paintcutpaste.com/pollock-splatter-painting/
- 15. #Cassandra13 API event stream event store roll-up cubes Ingest Processing dashboard queries programatic interface API event stream event store roll-up cubes Ingest Processing dashboard queries programatic interface Cassandra stores raw events, aggregates, data model definition Acunu Analytics maps events and SQL-like queries into C* ops API event stream event store roll-up cubes Ingest Processing dashboard queries programatic interfacePROCESSING AT INGEST JSON, CSV, log ingest via RESTful HTTP API, Flume, Storm, AMQP Storm, MQ HTTP Acunu Dashboards provides rich, real-time, embeddable visualizations SELECT AVG(r) FROM metrics GROUP BY host; AQL Alerting ! Cubes MILLISECOND QUERIES API event stream event store roll-up cubes Ingest Processing dashboard queries programatic interface API for rich queries, threshold alerting Backfill historic results for new cubes to enable agile schema changes
- 16. #Cassandra13 Apache,Apache Cassandra, Cassandra, Flume, and the eye logos are trademarks of the Apache Software Foundation. @timmoreton @acunu Thanks!