RDBMS:
Vertically scaled
Strong ACID guarantee
Relational support
Performance cost with full-text integration
High query latency with large dataset, especially for operations like Group By
Indexes needs to be built for all sort possibilities offline
Sensei:
Horizontally scaled
Relaxed consistency with high durability guarantees
Data is streamed in, so atomicity and isolation is to be handled by the data producer
Full-text search support
Low query latency with arbitrarily large dataset
Dynamic sorting, index is already built for all sortable fields and their combinations