Database

Common Table Expressions and recursive queries for hierarchical data, graph traversal, and complex query composition

Index types, design strategies, and maintenance for optimal query performance in relational databases

JSON storage, querying, indexing, and manipulation in PostgreSQL and MySQL for semi-structured data

Database schema migration strategies for safe, reversible, and zero-downtime changes to production databases

Techniques for analyzing and optimizing SQL query performance using execution plans, statistics, and query rewrites

Stored procedures, functions, and triggers for encapsulating business logic and automating actions within the database

Transaction management, ACID properties, isolation levels, and concurrency control in relational databases

SQL window functions for analytics, ranking, and running calculations over partitioned result sets