System design interview is pretty common these days, specially if you are having experience of more than 4-5 years. It is infact a good way to judge a candidate about his software designing or architecting skills.
Facebook does have a System design interview. They tries to match your skills with the right kind of System Design Interview. Be clear with your recruiter about this, and you should clarify with your recruiter about what kind of questions will be there in this interview. You can actually ask them for a sample question from each category, and they are very helpful.
Facebook System design interview actually involves two broad categories which decides what kind of detailing you can expect in a system design interview.
Backend Engineer System Design Interview
This type of interview starts by a fairly defined problem and a focus on the backend system components and their interactions. The focus is on the standard parts of building a solution.
An example question is “Design a URL shortener”. There is some ambiguity and product design elements to this question, typically used as extensions once the initial solution has been proposed.
What you can expect here:
- Solution of the problem
- Scalability (Important) If you have worked on how to scale an app, you should choose this kind of interview. You should be clear on how to handle large number of calls and how to scale well.
- Details about each backend technology You should be clear about which technologies to use for particular use case. Example: which database, which caching, which communication etc
- Sharding You should know how to shard your database for large scale applications.
- Trade-offs in different technologies
- Monitoring/health of systems
Fullstack Engineer System Design Interview
This is also called as Product Design Interview. The focus is typically on the more holistic parts of building a software solution and less on focus on the backend components. A full stack design interview question typically has a lot more product-oriented questions to be considered and more lee way in terms of the direction that the interview question can go in.
An example question is, “Design the news feed API”. In discussing this question you are expected to explore the problem domain more fully, to think about the entities in the system, a logical data model, potentially the physical data model (how the data is stored within the client and the server), the APIs and the interactions between the servers and clients.
What you can expect here:
- Solution of the problem
- Load balancers
- Sharding
- Caching
- Distribution of Data
- Speed/space/time trade-offs
- Pagination
- APIs
- Client/Server communication
- Partitioning
