Example Concept: Indexing is a crucial optimization technique that involves creating indexes on columns frequently used in WHERE clauses, JOIN conditions, or as part of aggregate functions. By doing so, the database engine can quickly locate and access the necessary data without scanning entire tables, significantly speeding up query execution. Additionally, query restructuring, such as using subqueries or common table expressions (CTEs) wisely, and partitioning large tables into smaller, manageable segments, can further enhance performance by reducing I/O operations and improving parallel processing capabilities.