Keepin it real (time) Cassandra in a real time bidding infrastructure

a dynamic auction process where each impression is bid for in (near) real time Advantages are cost efficiency, higher performance and greater granularity with targeting and measurement. bidding-the-next-big-thing/ What is real time bidding (RTB)?

I'm more of a visual person...

Where Cassandra lives True 2-tier Cassandra does caching Cassandra does storage AdServers talk to any node

Requirements Low latency reads (exchanges have max request time) Low latency writes (record win for frequency capping) Other Information (bulk/back loaded) Large volumes of data ~ 10 TB (RF=3) NOT having 1 to 1 Disk/RAM Ratio Uptime (surviving node failures) :) Manageability/Usability

Cassandra and writes Writes to sorted memtable (in memory) + commit Memtables flush periodically to Sstables (thresholds) Compacts SStables (thresholds) Results in 1-3 ms writes typical !Sweet! So all good right? Bulk load can pollute caches Model requires compaction (vs write in place)

Cassandra and Reads SSTables are sorted by key (>1SStables Bloom filters) Two Cassandra caches KeyCache and RowCache VFS Cache + mmap (efficient for non cached items) Results in 3-10ms(avg) Reads !!That's nice!! (Borat voice) So its all good right ? more data = more ram | faster disk | more nodes Cache tuning for multiple Column Families is a moving problem

Cassandra and Uptime Cassandra handles replication for you Multiple active nodes to serve reads and writes! Nodes get themselves back into sync HH and Read Repair Results in Minor failures may not even be visible on the client Restart without dealing with replication logs etc. So its all good right? Do see the occasional OOM Gossip protocol has turned into tabloid protocol

NoSQL Adventure time