Storing Time Series Metrics With Cassandra and Composite Columns
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This document discusses storing and aggregating time series metrics in Cassandra using counters and composite columns. It provides an example schema using multiple column families partitioned by time period (day, hour, minute, second). Data is inserted by incrementing counters for composite column names representing the aggregated values. Retrieval involves multiget queries on ranges of composite column names to retrieve aggregated counts for a time period.
![What it looks like in Cassandra
valsample1: String = "10/12/2011 11:22:33 GET /sample?animal=duck&sound=quack&home=pond”
valsample4: String = "10/12/2011 11:22:33 GET /sample?animal=cat&sound=purr&home=house”
valsample5: String = "10/12/2011 11:22:33 GET /sample?animal=lion&sound=purr&home=zoo”
valsample6: String = "10/12/2011 11:22:33 GET /sample?animal=dog&sound=woof&home=street"
[default@FixtureTestApophis] get ByDay[20111012];
=> (counter=animal#sound#home=cat#purr#house, value=70)
=> (counter=animal#sound#home=dog#woof#street, value=20)
=> (counter=animal#sound#home=duck#quack#pond, value=98)
=> (counter=animal#sound#home=lion#purr#zoo, value=70)
=> (counter=animal#sound=cat#purr, value=70)
=> (counter=animal#sound=dog#woof, value=20)
=> (counter=animal#sound=duck#quack, value=98)
=> (counter=animal#sound=lion#purr, value=70)
=> (counter=animal=cat, value=70)
=> (counter=animal=dog, value=20)
=> (counter=animal=duck, value=98)
=> (counter=animal=lion, value=70)
=> (counter=sound#animal=purr#cat, value=42)
=> (counter=sound#animal=purr#lion, value=42)
=> (counter=sound#animal=quack#duck, value=43)
=> (counter=sound#animal=woof#dog, value=20)
(counter=total=, value=258)
https://github.com/joestein/apophis
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Storing Time Series Metrics With Cassandra and Composite Columns
- 1. Storing Time Series Metrics Implementing Multi-Dimensional Aggregate Composites with Counters For Reporting /* Joe Stein http://www.linkedin.com/in/charmalloc @allthingshadoop @cassandranosql @allthingsscala @charmalloc */ Sample code project up at https://github.com/joestein/apophis 1
- 2. Medialets What we do 2
- 3. Medialets • Largest deployment of rich media ads for mobile devices • Over 300,000,000 devices supported • 3-4 TB of new data every day • Thousands of services in production • Hundreds of Thousands of simultaneous requests per second • Keeping track of what is and was going on when and where used to be difficult before we started using Cassandra • What do I do for Medialets? – Chief Architect and Head of Server Engineering Development & Operations. 3
- 4. What does the schema look like? CREATE COLUMN FAMILY ByDay Column Families hold WITH default_validation_class=CounterColumnType your rows of data. Each AND key_validation_class=UTF8Type AND comparator=UTF8Type; row within each column family will be equal to the CREATE COLUMN FAMILY ByHour time period you are WITH default_validation_class=CounterColumnType dealing with. So an AND key_validation_class=UTF8Type AND comparator=UTF8Type; “event” occurring at 10/20/2011 11:22:41 will CREATE COLUMN FAMILY ByMinute WITH default_validation_class=CounterColumnType become 4 rows AND key_validation_class=UTF8Type AND comparator=UTF8Type; BySecond = 20111020112141 ByMinute= 201110201122 CREATE COLUMN FAMILY BySecond ByHour= 2011102011 WITH default_validation_class=CounterColumnType ByDay=20111020 AND key_validation_class=UTF8Type AND comparator=UTF8Type; 4
- 5. Why multiple column families? http://www.datastax.com/docs/1.0/configuration/storage_configuration 5
- 6. Ok now how do we keep track of what? Lets setup a quick example data set first • The Animal Logger – fictitious logger of the world around us – animal – food – sound – home • YYYY/MM/DD HH:MM:SS GET /sample?animal=X&food=Y – animal=duck&sound=quack&home=pond – animal=cat&sound=meow&home=house – animal=cat&sound=meow&home=street – animal=pigeon&sound=coo&home=street 6
- 7. Now what? Columns babe, columns make your aggregates work • Setup your code for columns you want aggregated – animal= – animal#sound= – animal#home= – animal#food= – animal#food#home= – animal#food#sound= – animal#sound#home= – food#sound= – home#food= – sound#animal= 7
- 8. Inserting data Column aggregate concatenated with values 2011/10/29 11:22:43 GET /sample?animal=duck&home=pond&sound=quack • mutator.insertCounter(“20111029112243, “BySecond”, HFactory.createCounterColumn(“animal#sound#home=duck#quack#pond”), 1)) • mutator.insertCounter(“20111029112243, “BySecond”, HFactory.createCounterColumn(“animal#home=duck#pond”), 1)) • mutator.insertCounter(“20111029112243, “BySecond”, HFactory.createCounterColumn(“animal=duck”), 1)) • mutator.insertCounter(“201110291122, “ByMinute”, HFactory.createCounterColumn(“animal#sound#home=duck#quack#pond”), 1)) • mutator.insertCounter(“201110291122, “ByMinute”, HFactory.createCounterColumn(“animal#home=duck#pond”), 1)) • mutator.insertCounter(“201110291122, “ByMinute”, HFactory.createCounterColumn(“animal=duck”), 1)) • mutator.insertCounter(“2011102911, “ByHour”, HFactory.createCounterColumn(“animal#home=duck#pond”), 1)) • mutator.insertCounter(“2011102911, “ByHour”, HFactory.createCounterColumn(“animal#sound#home=duck#quack#pond”), 1)) • mutator.insertCounter(“2011102911, “ByHour”, HFactory.createCounterColumn(“animal=duck”), 1)) • mutator.insertCounter(“20111029, “ByDay”, HFactory.createCounterColumn(“animal#sound#home=duck#quack#pond”), 1)) • mutator.insertCounter(“20111029, “ByDay”, HFactory.createCounterColumn(“animal#home=duck#pond”), 1)) • mutator.insertCounter(“20111029, “ByDay”, HFactory.createCounterColumn(“animal=duck”), 1)) 8
- 9. The implementation, its functional kind of like “its electric” but without the boogie woogieoogie def r(columnName: String): Unit = { aggregateKeys.foreach{tuple:(ColumnFamily, String) => { val(columnFamily,row) = tuple if (row !=null &&row.size> 0) rows add (columnFamily -> row has columnName inc) //increment the counter } } } def ccAnimal(c: (String) => Unit) = { c(aggregateColumnNames("Animal") + animal) } //rows we are going to write too aggregateKeys(KEYSPACE "ByDay") = day aggregateKeys(KEYSPACE "ByHour") = hour aggregateKeys(KEYSPACE "ByMinute") = minute aggregateColumnNames("Animal") = "animal=” ccAnimal(r) 9
- 10. Retrieving Data MultigetSliceCounterQuery • setColumnFamily(“ByDay”) • setKeys("20111029") • setRange(”animal#sound=","animal#sound=~",false,1000) • We will get all animals and all of their sounds and counts for that day • setRange(”sound#animal=purr#",”sound#animal=purr#~",false ,1000) • We will get all animals that purr and their count • What is with the tilde? 10
- 11. Sort for success Not magic, just Cassandra 11
- 12. What it looks like in Cassandra valsample1: String = "10/12/2011 11:22:33 GET /sample?animal=duck&sound=quack&home=pond” valsample4: String = "10/12/2011 11:22:33 GET /sample?animal=cat&sound=purr&home=house” valsample5: String = "10/12/2011 11:22:33 GET /sample?animal=lion&sound=purr&home=zoo” valsample6: String = "10/12/2011 11:22:33 GET /sample?animal=dog&sound=woof&home=street" [default@FixtureTestApophis] get ByDay[20111012]; => (counter=animal#sound#home=cat#purr#house, value=70) => (counter=animal#sound#home=dog#woof#street, value=20) => (counter=animal#sound#home=duck#quack#pond, value=98) => (counter=animal#sound#home=lion#purr#zoo, value=70) => (counter=animal#sound=cat#purr, value=70) => (counter=animal#sound=dog#woof, value=20) => (counter=animal#sound=duck#quack, value=98) => (counter=animal#sound=lion#purr, value=70) => (counter=animal=cat, value=70) => (counter=animal=dog, value=20) => (counter=animal=duck, value=98) => (counter=animal=lion, value=70) => (counter=sound#animal=purr#cat, value=42) => (counter=sound#animal=purr#lion, value=42) => (counter=sound#animal=quack#duck, value=43) => (counter=sound#animal=woof#dog, value=20) (counter=total=, value=258) https://github.com/joestein/apophis 12
- 13. A few more things about retrieving data • You need to start backwards from here. • If you want to-do things adhoc then map/reduce is better • Sometimes more rows is better allowing more nodes to-dowork – If you need to look at 100,000 metrics it is better to pull this out of 100 rows than out of 1 – Don’t be afraid to make CF and composite keys out of Time+ Aggregate data • 20111023#animal=duck • This could be the row that holds ALL of the animal duck information for that day, if you want to look at 100 animals at once with 1000 metrics for each per time period, this is the way to go 13
- 14. Q&A Medialets The rich media adplatform for mobile. connect@medialets.com www.medialets.com/showcase 14