introduction to Apache Cassandra distributed database

1. Cassandra
Prophecy
Igor Khotin
E-mail: khotin@gmx.com

2. Background
● 11+ years in the IT industry
● 6+ years with Java
● Flexible design promoter
● Agile-junkie

4. highly scalable, eventually consistent,
distributed, structured key-value store

5. Decentralized
● P2P
● No SPOF
● No network bottlenecks

6. Fault Tolerant
● High Availability
● Replication and redundancy
● Node replacement & no downtime
● Multiple racks & datacenters

7. Elastic Scalability
● Scales up and down
● Just add or remove nodes
● Linear scalability
● Low maintenance cost

8. Tunable consistency
● Different consistency levels
● Consistency vs. latency

9. Rich Data Model
● Goes beyond simple key-value
● Values could be indexed
● Flexible schema

10. Scale up problem

11. Sharding doesn't solve it

13. Google File System & Google BigTable

15. Amazon Dynamo

17. Cassandra
by Avinash Lakshman and Prashant Malik

18. Cassandra
used in Inbox Search

19. Open sourced in July 2008

20. March 2009
Accepted to Apache Incubator

21. February 2010
Top-Level Apache Project

22. late 2010...
Cassandra abandoned
Messaging moved to HBase

23. October 2011
Release 1.0

24. November 30, 2011
Release 1.0.5
(current stable)

25. Moving forward fast...

27. Brewer's CAP Theorem

28. Data Model

29. Column Family

30. Column sorting
● ASCII Design decision
● UTF8
● Bytes
● Long
● LexicalUUID
● TimeUUID
● Custom

31. Denormalization

32. Denormalization

33. Design for queries

34. Keyring

35. Keyring

36. Keyring

37. Keyring

38. Keyring

39. Keyring

40. Keyring

41. Keyring

42. Gossip

43. Optimized for writes

44. Optimized for writes
● No reads
● No seeks
● No b-trees
● Fast
● Row - atomic

46. Tunable Consistency

47. Tombstone

48. Low Level Clients
● Thrift
● IDL and binary communication protocol
● Multiple languages support
● Really sucks
● Avro
● Better than Thrift, but sucks anyway

49. High Level Clients
● Feature-rich
● Connection pool
● Load-balancing
● Fail-over
● Hector, Pelops... (Java)
● Pycassa... (Python)
● Fauna (Ruby)
● ...

50. CQL
● SQL for NoSQL
● CREATE KEYSPACE, CREATE COLUMNFAMILY, CREATE INDEX
● USE, SELECT, UPDATE, DELETE...
SELECT population FROM city
WHERE KEY = 'Paris'
USING CONSISTENCY QUORUM

53. Understand your problem

54. Understand your problem
Find appropriate solution

56. Don't let default solutions to be imposed on you

57. Hard to choose?

58. Leaders will emerge

60. Resources
● http://cassandra.apache.org
● Dynamo: Amazon’s Highly Available Key-value Store
● Cassandra - A Decentralized Structured Storage System
● Bigtable: A Distributed Storage
System for Structured Data

61. Contacts
E-mail: khotin@gmx.com
Blog: www.ikhotin.com
Twitter: chaostarter

62. Questions?