QUERY OPTIMIZATION AND QUERY PLANNER MECHANISMS IN POSTGRESQL: PERFORMANCE ANALYSIS AND PRACTICAL IMPLEMENTATION

PostgreSQL is a highly advanced open-source relational database management system widely used in modern enterprise applications. As database sizes increase, query execution efficiency becomes a critical factor affecting system performance. Query optimization is a key mechanism that allows PostgreSQL to determine the most efficient method of executing SQL queries. This study analyzes PostgreSQL query optimization techniques, focusing on the internal query planner, execution strategies, cost estimation models, and performance analysis. Experimental comparisons between optimized and non-optimized queries are presented to demonstrate performance improvements. The article also discusses practical optimization methods and best practices for large-scale database systems.