1. Get On Demand Education Anytime, Anywhere
with Coursera and DataStax
Daniel Chia
@DanielJHChia
Software Engineer, Infrastructure
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Webinar Housekeeping

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1 About Coursera
2 Requirements for a modern database platform
3 MySQL: The challenges and why we migrated
4 Cassandra versus MongoDB and HBase
5 Why Apache Cassandra and DataStax
6 Finding success with DataStax Enterprise
4
Today’s Agenda

5. © 2015 DataStax, All Rights Reserved. 5
100+ Partners
> 1000 Courses
11 Million learners

6. A Peek into Coursera
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• Video courses
• Announcements for videos and assignments

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A Peek into Coursera
Your Final Project
This is your chance to apply the course concepts to real-world situations
• In-video quizzes
• Assignment and evaluation

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A Peek into Coursera
• Web, Android + iOS
• Identify verified certificate

9. Dropping Courses to On-Demand
• The most common complaint we hear from learners is that
courses run infrequently and are not accessible.
© 2015 DataStax, All Rights Reserved. 9
….so we created On-Demand.
55%
of learners cite missing a
deadline as the reason for
dropping a course

10. Application Availability Matters
© 2015 DataStax, All Rights Reserved. 10
• A global reach of learners – 11
Million worldwide
• Application downtime leads to poor
customer experience
• Especially relevant to in-video
quizzes & assessment

11. Requirements for A Modern Database Platform
• 99.99% application availability guarantees always-on learning
experiences
• Reliable performance at massive scale for over 11 million users
• Ease of use operationally
• Application performance with low latency
• Multi-region writes replication
© 2015 DataStax, All Rights Reserved. 11

12. Technical Environment @Coursera
• 100% hosted on AWS
• Service-oriented architecture
• Mix of MySQL and DataStax for persistence
© 2014 DataStax, All Rights Reserved. 12

13. • Normalized SQL data model causes
very expensive queries
• Limitations in innovation of new
features due to scale concerns
• MySQL’s single points of failure
causes unexpected application
downtime
© 2015 DataStax, All Rights Reserved. 13
Challenges with MySQL

14. Scalability Limits and Rigidity with MySQL
© 2015 DataStax, All Rights Reserved. 14
Uh-oh…
Doesn’t fit in existing sharding
Limited Scalability with MySQL
• Scale up
• Scale out (sharding)

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• Columnar model
• Tunable consistency
• Multi-data center replication
• Thriving Open Source community with
enterprise support
• Easier setup
C*.

16. Cassandra vs. MongoDB & HBase
© 2015 DataStax, All Rights Reserved. 16
Cassandra vs. MongoDB
• Used to run it as KV store, but
supports document model
• Master would sometimes lock up,
but not failover
• Has indexing
Cassandra vs. HBase
• Many things to set up
• Only runs in one AZ out of the box
on AWS
• Consistent model
• Multi-region replication with
Cassandra

17. DataStax Enterprise Platform Overview
In-Memory
In-memory database option allows data to be stored on RAM
instead of on disk. Delivers fast response times on frequently
accessed data for transactional applications.
Search
Built-in enterprise search feature on Cassandra
data via Solr. Allows you to search vast volumes of
data quickly to deliver optimal performance.
Analytics
Streaming data, real-time and batch analytics on
Cassandra data with external Hadoop integration. Helps
consume and analyze customer data to deliver the most
personalized experience.
Expert Support
24x7 support plus software maintenance, bug fixes,
and performance reviews. Emergency bug fixes and
support gives customers the peace of mind that their
mission critical applications are always online.
Visual Admin
DataStax OpsCenter is a visual, browser based interface for
managing Cassandra and DataStax clusters. Visual
management for administration, performance monitoring
supplies greater ease of use and reduces TCO.
Management Services
Automatic services transparently handle maintenance and
performance tuning. Enables IT departments to easily
manage health of the database reducing operational
expenditure.
Cassandra Certified
DataStax production certifies Apache Cassandra. Gives customers
the commercial confidence that Cassandra has been through a
rigorous testing process at massive scale along with additional
enterprise functionality.
Security
Comprehensive enterprise security feature set including
encryption, audit logging, authentication and LDAP/Active
Directory integration. Protects customer data against
unauthorized access and meet regulatory and compliance
requirements.

18. Performance Metrics
• Read latency: 1ms, 5ms, 20ms (median, p95, p99)
• Write latency: 1ms, 2ms, 3ms (median, p95, p99)
• Many rolling restarts without application downtime
© 2014 DataStax, All Rights Reserved. Company Confidential 18

19. DataStax ≠ [database XYZ]
© 2015 DataStax, All Rights Reserved. 19
- Albert Einstein
“But if you judge a fish by its ability to climb a tree, it
will live its whole life believing that it is stupid.”

20. Migration from MySQL to DataStax Enterprise
• Transition needs time, carries some risk
– Pick one feature first
• Mindset shift & expertise
• Data modeling consulting
• Libraries / Patterns / Data-as-a-Service
© 2015 DataStax, All Rights Reserved. 20

21. From SQL to CQL - Mindset Shift
• Everyone knows SQL
• Not everyone knows Cassandra / NoSQL
• Need to know queries beforehand
• Our experience with CQL
© 2015 DataStax, All Rights Reserved. 21

22. Thank you!
Input questions at any time
using the online interface