Will Cross's blog post from September 8, 2022, delves into SQL performance best practices, emphasizing the pivotal role of indexes for optimizing database queries. Highlighting that efficient indexing can notably enhance performance, the article outlines several rules: filtering queries to avoid full table scans, sorting queries to expedite results, and "covering" queries to bypass table access entirely. Using CockroachDB as an example, the author demonstrates how using statement plans with EXPLAIN ANALYZE can provide insight into database behavior, facilitating informed indexing decisions. The post illustrates how constructing a composite index, such as one on both email and datetime, can reduce the workload by limiting row scans and sorts, thus significantly improving query execution time. A covered query, which avoids accessing the table by utilizing indexed data, is presented as the optimal solution for read performance. However, the author cautions against over-indexing due to the overhead of maintaining consistency with the table data, noting that large fields should be excluded from indexes to prevent excessive index size. The blog encourages leveraging tools like EXPLAIN plans and seeking community support for unexpected issues, while also promoting additional learning resources on SQL performance and best practices.