1. Cassandra in
| Online Advertising:
Real Time Bidding
the prospect engine for brands.

2. Who are we?
Costa Sevdinoglou & Edward Capriolo

3. Impressions look like…

4. A High Level look at RTB
1. Browsers visit Publishers and create impressions.
2. Publishers sell impressions via Exchanges.
3. Exchanges serve as auction houses for the impressions
4. On behalf of the marketer, m6d bids the impressions via the
auction house. If m6d wins, we display our ad to the
browser.

5. Performance and Data
• Billions and billions of bid requests a day
• A single request can result in multiple
Cassandra Operations!
• One cluster is just under 10TB and growing
• Low latency requirement below 120 ms typical
• Limited data available to m6d via the exchange

6. Segment Data
Segments are how we assign product or service
affinity to a group of users. User’s we consider to be
like minded with respect to a given brand will be
placed in the same segment.
Segment Data is just one component of our
overarching data model.
Segments help to reduce the number of calculations
we do in real time.

7. Old Approach for Segment Data
Application Nodes
(Tomcat + MySQL )
Limitations
•Periodically updated.
MySQL Data Push Event Logs •Only subsection of
the data.
•Cluster performance
is effected during a
data push.
Aggregation Hadoop

8. Cassandra Approach
for Segment Data
Application Nodes Better!
(Tomcat + Less • Updating in real time now
MySQL Usage) possible
• Distributed not duplicated
• Less complexity to manage
• Storing more information
• We can now bid on users
Cassandra sooner!

9. One Ring to rule them all
http://askyyy.blog.163.com/blog/static/12345759920104288193
99/

10. Peer to Peer
per operation replication
 Fail fast, self-healing
 Each write goes to all natural endpoints
 Hinted handoff if destination is down
 Repair on Read
 No more:
 STOP SLAVE; SET GLOBAL
SQL_SLAVE_SKIP_COUNTER = 1; START
SLAVE;

11. Multi Data Center
 No designing and managing complex replication topologies
 create keyspace world
with placement_strategy =
'org.apache.cassandra.locator.NetworkTopologyStrategy'
and strategy_options={1:3, 2:3, 3:3};
 The same process as single data center
 No log shipping, or separate processes to run

12. Monitoring & Management
 Many Many things to monitor with JMX
 Nice command line tools
 Most values can be tweaked at run time

13. Capacity Planning
 How many
 Rows
 Columns
 Size of Average Column
 Latency requirements
 Throughput read and writes per sec

14. Unit Tests FTW!

15. Max 2 billion columns per row
 Awesome
 Unless you accidentally write 2 billion
columns to a row key named “null”
 Check maxRowSize JMX
 Watch logs for messages about compacting
large rows

16. Local (NYC) Meetups
 www.meetup.com/NYC-Cassandra-User-
Group/