Databases Demystified Chapter 10 – Query Planning and Optimization

Query planning and optimization is crucial for efficient database performance. SQL, a declarative language, allows users to describe the desired output rather than providing direct execution instructions. When executing a query, the database generates a plan that outlines the steps it will follow to return results. The query planner, a complex component of modern databases, creates this plan. Reviewing a query plan can help identify areas for optimization, such as predicate pushdown and adding indexes. Additionally, data distribution in distributed databases impacts query efficiency, with more efficient joins possible when data is distributed based on relevant join conditions.