Interview Questions and Answers

Performance optimization involves proper indexing, query optimization, and denormalization when necessary. It also includes choosing appropriate data types, partitioning tables, and optimizing SQL queries.

Example:

Example: Indexing frequently queried columns in a 'User' table to speed up search operations.

Concurrency control mechanisms, such as locking or optimistic concurrency control, are used to manage simultaneous access to data and prevent conflicts during transactions.

Example:

Example: Using row-level locking to ensure that two transactions don't modify the same row simultaneously.

Handling historical data involves using slowly changing dimensions (SCDs), where changes to data over time are tracked. SCD types include Type 1 (overwrite), Type 2 (add new row), and Type 3 (add columns).

Example:

Example: Using Type 2 SCD to add a new row for an employee when their department changes over time.