Consider the fundamental components of a pastebin service: storage, retrieval, and access control. How might these be designed to handle large volumes of data efficiently?

Think about the trade-offs between using a relational database (e.g., MySQL) and a NoSQL database (e.g., MongoDB) for storing pastebin content. What are the implications for scalability and performance?

Explore advanced techniques like sharding, caching (e.g., Redis), and CDNs to optimize read/write operations and reduce latency for a global user base. How would you implement these in a distributed system?