How did you optimize the running time of your projects? Which database did you use in your project and why? Why not NoSQL Database? Difference between SQL and NoSQL. How does NoSQL support horizontal scalability? Tell about ACID and CAP theorem. Are consistency and availability both possible simultaneously? Tell about isolation levels and indices in SQL database. Advantages and disadvantages of indices. What is idempotency in API and how can it be achieved? Difference between Put and Patch. Difference between optimistic and pessimistic locking?