Introduction to MySQL Indexes: Why Should You Understand Indexes Even for Simple Queries?

The article explains why understanding MySQL indexes is necessary even for simple queries. An index is a special data structure (e.g., B+ tree) that maps key field values to data locations, transforming full table scans into precise positioning and significantly improving query efficiency. The reasons why even simple queries require indexes include: slow queries without indexes as data volume grows, requiring proactive planning; beginners often writing inefficient SQL (e.g., redundant conditions); and laying the foundation for complex queries (e.g., multi-table joins). Common index types include primary key, regular, unique, and composite indexes, each suited for different scenarios. Key considerations include avoiding over-indexing (e.g., on frequently updated fields) and ensuring indexes are not invalidated by using functions/expressions. The `EXPLAIN` command can verify index effectiveness. In summary, indexes are core to performance optimization; appropriate indexes should be designed based on usage scenarios to accommodate data growth and complex queries.