No resource is perfect. Observers note that Sen’s style sometimes leans heavy on theoretical database internals (B-Tree vs. LSM Tree), which, while impressive, may be overkill for a 45-minute interview. Additionally, his advanced videos assume a working knowledge of networking (TCP/UDP, TLS) that junior engineers may lack.
Everyone draws a SQL database, but no one discusses the index. Without an index on user_id , a SELECT query is O(n). With a B-Tree index, it is O(log n). This distinction wins offers. Gaurav Sen System Design