Cost-based Query Optimization

This lecture covers the fundamentals of cost-based query optimization in database systems, including heuristics, cost estimation, selectivity estimation, and join cardinality estimation. It explains how to generate cost estimates for executing query plans, optimize join orders, and estimate the number of intermediary results. The instructor discusses various techniques such as histograms, equi-width, and equi-depth histograms for accurate selectivity estimation. The importance of join cardinality estimates for optimizing join operations is also highlighted, emphasizing the need to reorder joins efficiently to minimize query execution costs.