Developers use the EXPLAIN

 The efficiency of backend server interaction with the main database is the primary factor determining the overall performance of any large-scale online project. When thousands of users simultaneously perform actions on the site (log in, check balances, activate promo codes), the database experiences enormous overload. If the code generates suboptimal, heavy SQL queries, the server infrastructure will quickly exhaust its resources, and the site will begin to freeze. A detailed guide on profiling and speeding up DBMS performance is available on the analytical resource https://loot-zino.org . The first and fundamental step in database optimization is proper index design. Indexes act like an alphabetical index in a book, allowing the DBMS to instantly find the required rows without having to scan the entire multi-million-row table. Developers use the EXPLAIN command to analyze query execution plans, which helps identify bottlenecks—rounds in which the system performs resource-intensive full table scans.