One pro tip for acing a system design interview is to read the engineering blog of the company you are interviewing with. You can get a good sense of what technology they use, why the technology was chosen over others, and learn what issues are important to engineers.
1. The Infrastructure Behind Twitter: Scale https://blog.twitter.com/engineering/en_us/topics/infrastructure/2017/the-infrastructure-behind-twitter-scale
2. Discovery and Consumption of Analytics Data at Twitter https://blog.twitter.com/engineering/en_us/topics/insights/2016/discovery-and-consumption-of-analytics-data-at-twitter
3. The what and why of product experimentation at Twitter
4. Twitter experimentation: technical overview https://blog.twitter.com/engineering/en_us/a/2015/twitter-experimentation-technical-overview