Kevin asks Wes to design Dropbox, with an emphasis on designing the data model and storage techniques to scale out.

Helpful links:
https://www.geeksforgeeks.org/design-dropbox-a-system-design-interview-question/

https://www.youtube.com/watch?v=PE4gwstWhmc

https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API

https://www.ibm.com/cloud/learn/object-storage

As Kevin prepares to start a new job at Instacart, he explains some ideas around how a company like Instacart could employ caching to improve the scalability of their services.

Show notes:

https://medium.com/datadriveninvestor/all-things-caching-use-cases-benefits-strategies-choosing-a-caching-technology-exploring-fa6c1f2e93aa

https://ieftimov.com/post/when-why-least-frequently-used-cache-implementation-golang/

https://github.com/donnemartin/system-design-primer#cache

https://memcached.org/  

https://redis.io/

Wes and Kevin talk about message queues, the problems they solve, and how they work. 

https://github.com/donnemartin/system-design-primer

http://highscalability.com/all-time-favorites/

https://netflixtechblog.com/

https://www.rabbitmq.com/tutorials/tutorial-one-python.html

P.S., Wes learned how to edit podcasts better thanks to this guide - https://podigy.co/podcast-editing-guide/, hopefully this podcast has the best audio quality yet!

Breaking away from the interview format, Wes and Kevin deep dive into SQL vs noSQL databases.

Show notes:

ACID compliance - https://mariadb.com/resources/blog/acid-compliance-what-it-means-and-why-you-should-care

CAP theorem 
https://www.ibm.com/cloud/learn/cap-theorem
https://mwhittaker.github.io/blog/an_illustrated_proof_of_the_cap_theorem
Cool article explaining the problem with saying you can have 2 out of 3 properties of CAP
http://martin.kleppmann.com/2015/05/11/please-stop-calling-databases-cp-or-ap.html

MongoDB - https://docs.mongodb.com/manual/introduction/

Wes asks Kevin to design the Facebook/Twitter Timeline with an emphasis on scaling to a large number of users.

I'd encourage you to pause where relevant to try to think through these designs yourself - it really helps the content sink in.

Helpful Links

RabbitMQ quick start documentation - https://www.rabbitmq.com/getstarted.html

Apache Kafka introductinon - https://kafka.apache.org/intro

In our first episode, Kevin gives Wes a mock interview on how to design google docs. 

Helpful links

The git storage technique we referenced is described in detail here - https://hypirion.com/musings/understanding-persistent-vector-pt-1 (Note that this is not git, but the same technique applies)

Website with algorithm for merge conflict resolution - https://operational-transformation.github.io/