This will be an interesting and sometimes fun session with a small demo. This session will answer some of your questions and force you to think about new questions. It will not be very technical, so it's ok for choose another more technical session from the schedule :) But if will decide to come, I can assure you, that you will not be disappointed. We will do a thought experiment with one famous public high-loaded website, will look at advantages and disadvantages of SQL and NoSQL databases, and will choose the best database engine for it.

1. SQL vs NoSQL
It’s Always a Hard Choice
Denis Reznik
Data Architect at Intapp, Inc.
Microsoft Data Platform MVP

2. About me
• Denis Reznik
• Kyiv, Ukraine
• Data Architect at Intapp, Inc.
• Microsoft Data Platform MVP
• Co-Founder Ukrainian Data Community
• PASS Regional Mentor, Central, and Eastern Europe
• Author of “SQL Server MVP Deep Dives 2” Chapter 19
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3. Database History
1960s 1970s 1980s 1990s 2000s Nowadays
Object
Databases
RDMS
Commercial
Success
SQL
RDBMS
Ingress
System R
E.F. Codd’s
Paper
CODASYL
IMS
NoSQL
(Johan Oskarsson)
NewSQL (?)
Google BigTable
Paper
Amazon Dynamo
Paper

4. NoSQL
SQL

5. Agenda
• Criteria #1
• Criteria #2
• Criteria #3
• Criteria #4
• Criteria #5
• Criteria #6
• Criteria #7

6. Tools
Criteria #1

8. Databases
Graph
Document
Relational
Column-Family
Key-Value

9. Domain
Criteria #2

10. Q&A Web Site (StackOverflow)

11. Domain Model
Questions Answers
Users
Comments Votes

12. Workload
Criteria #3

13. Sample Workload
• 4 million users
• 8 million questions
• 40 million answers
• As a network #54 site for traffic in the world
• 560 million page views a month
• Peak is more like 2600-3000 requests/sec on most
weekdays.
source: https://www.youtube.com/watch?v=t6kM2EM6so4

14. Scalability
Criteria #4

15. Scalability
• Scale up
• Very easy to scale
• Always have a limit
• Hardware is expensive
• Scale-out
• Relatively tricky scaling
• Theoretically infinite scale
• Can be done on commodity hardware

16. Durability
Criteria #5

17. Durability
ACID
• D – for Durability
• Not all NoSQL databases are
durable (at least by default)

18. Cost
Criteria #6

19. Cost
• Hardware
• Big servers are expensive
• Small servers are cheep
• Small servers can be easily replaced
• License
• A lot of NoSQL databases are free
• There are free RDBMS as well
• Scale Out is more useful for free software
• Support
• MSSQL forgives you more than MySQL

20. Knowledge
Criteria #7

22. Polyglot Persistence
Criteria #8

23. Real Architecture of StackOverflow
source: https://www.youtube.com/watch?v=t6kM2EM6so4

24. Summary
• Tools
• Domain
• Workload
• Scalability
• Durability
• Cost
• Knowledge
• Polyglot Persistence

25. More Points
• “Respect the problem” (c)
• Think about the future workload grows
• Think about the future application changes
• Database itself, even if it is blazing fast, is not a purpose of
not to use cache
• Consider cloud database offers
• Consider Polyglot Persistence
• Consider using service tier for data access in application
• Easier database exchange
• Tire scaling
• A/B testing

26. Thank you!
Denis Reznik
Twitter: @denisreznik
Email: denisreznik@gmail.com
Blog: http://reznik.uneta.com.ua
Facebook: https://www.facebook.com/denis.reznik.5
LinkedIn: http://ua.linkedin.com/pub/denis-reznik/3/502/234