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Cassandra at Hailo

Dave Gardner
February 04, 2014

Cassandra at Hailo

My talk at Cassandra London on 4th February 2014. Covers how Hailo use Cassandra.

Dave Gardner

February 04, 2014

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  1. CASSANDRALONDON2014 •  The world’s highest-rated taxi app – over 11,000

    five-star reviews •  Over 500,000 registered passengers •  A Hailo hail is accepted around the world every 4 seconds •  Hailo operates in 15 cities on 3 continents from Tokyo to Toronto in nearly 2 years of operation Facts and figures
  2. CASSANDRALONDON2014 “NoSQL DBs trade off traditional features to better support

    new and emerging use cases” Andy Gross, Riak http://www.slideshare.net/argv0/riak-use-cases-dissecting-the-solutions-to-hard-problems
  3. CASSANDRALONDON2014 •  More widely used, tested and documented software • 

    Ad-hoc querying •  Talent pool with direct experience What are we trading off?
  4. CASSANDRALONDON2014 A history lesson •  Version 1 launched in London

    in November 2010 2 x PHP/MySQL web apps + 1 x Java/MySQL backend •  Version 1.5 launched in Dublin, then 13 others Transitioning to global Java and PHP services built on C* •  Version 2.0 launched 2013 Global Java/Go services built on C* running on a common platform
  5. CASSANDRALONDON2014 Why Cassandra? •  A desire for greater resilience –

    “become a utility” Cassandra is designed for high availability •  Plans for international expansion around a single consumer app Cassandra is good at global replication •  Expected growth Cassandra scales linearly for both reads and writes •  Prior experience I had experience with Cassandra and could recommend it
  6. CASSANDRALONDON2014 Operational Cluster Stats Cluster ap-southeast-1 us-east-1 eu-west-1 us-east-1 eu-west-1

    AWS VPCs with Open VPN links 3 AZs per region m1.xlarge machines 5.4TB storage; 600GB data
  7. AZ1 eu-west-1 AZ1 AZ2 AZ2 AZ3 AZ3 AZ1 us-east-1 AZ1

    AZ2 AZ2 AZ3 AZ3 AZ1 ap-southeast-1 AZ1 AZ2 AZ2 AZ3 AZ3 CASSANDRALONDON2014
  8. CASSANDRALONDON2014 C* all the things Stats Service C* many of

    the things Enlightenment Time Happiness
  9. CASSANDRALONDON2014 “How can you have wrong data model in C*

    when a CF is basically a hash in a hash” Anonymous Engineer at Hailo
  10. CASSANDRALONDON2014 There will probably be an experience gap •  Have

    an advocate - get someone who will sell the vision internally •  Learn the theory - teach each team member the fundamentals •  Make an effort to get everyone on board
  11. CASSANDRALONDON2014 Watch out for drift •  Cassandra can often be

    low maintenance – be pro-active •  Keep enough disk space for compactions •  Spot data model problems before they explode
  12. CASSANDRALONDON2014 We like Cassandra •  Solid design •  HA characteristics

    •  Easy multi-DC setup •  Simplicity of operation
  13. CASSANDRALONDON2014 Lessons for successful adoption •  Have an advocate, sell

    the dream •  Learn the fundamentals, get the best out of Cassandra •  Invest in tools to make life easier •  Keep management in the loop, explain the trade offs
  14. CASSANDRALONDON2014 The future •  We will continue to invest in

    Cassandra as we expand globally •  We will hire people with experience running Cassandra •  We will focus on expanding our reporting facilities •  We aspire to extend our network (1M consumer installs, wallet) beyond cabs •  We will continue to hire the best engineers in London, NYC and Asia