Chronologic and Cassandra at Gowalla
summary
Chronologic is an activity-feed service that stores events, objects and sub‑events in Cassandra and serves fully materialized timelines over a REST JSON API; it uses Ruby + Sinatra + Cassandra via Thrift, implements per-request durability and quorum tuning, fans out events to subscriber timelines, replicates referenced objects, and enforces privacy handled at read time rather than on write. It runs in production at Gowalla, returns timelines and incremental updates in one request, and demonstrably works for fast‑growing social feeds. Chronologic: event store + fan‑out
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chapters (18)
- 0:00Start
- 0:53What Is Cassandra
- 7:03Why Are We Using Cassandra at Koala
- 9:40Use Cassandra for Caching Social Graphs from Other Networks
- 10:32What Do I Want To Use Cassandra for in the Future
- 12:25What Would I Not Use Cassandra for
- 13:57Cassandra's Data Model
- 14:37Secondary Indexes
- 16:11Ruby Cassandra Driver
- 17:57Social Graphs
- 20:18Chronologic
- 20:41Events and Object References
- 22:57Applications Publish Events
- 26:49Social Graph
- 28:09Timeline Index
- 29:58Social Graph Api
- 37:16Replace Redis Use with Cassandra
- 42:33Durability Consistency Settings
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