Summary
This guide presents a collection of 30 SQL performance tips designed to enhance query efficiency. It outlines best practices in fetching, filtering, aggregating, joining data, and indexing. The document begins with strategies for fetching data, recommending the selection of only necessary columns and limiting rows for exploration. It warns against the use of DISTINCT and ORDER BY unless required, as these can hinder performance. Additionally, it suggests creating non-clustered indexes and avoiding functions that restrict index usage. In the section on joining data, it emphasizes understanding join types and using explicit joins for better clarity and performance. The guide also discusses the importance of optimizing data types, maintaining primary keys, and regularly reviewing indexes. Furthermore, it covers the use of CTE for simplifying queries, the implications of nested loops on execution plans, and the necessity of updating table statistics to support efficient query optimization.
