The Art of MySQL Index Order: A Deep Dive from Composite Indexes to the Query Optimizer

This article provides a deep dive into the philosophy of MySQL composite index design. Starting with the core 'Leftmost Prefix Principle,' we tackle the practical problem of designing efficient indexes for complex queries involving time ranges. We'll also debunk a common myth about why a composite index is far superior to multiple separate indexes. Finally, the article explains why the order of the WHERE clause doesn't matter and introduces how to use the EXPLAIN tool to validate your indexing strategy, helping you become a database performance tuning expert.