Refactoring Legacy PHP Code for Efficient Database Queries in a High-Load Environment
I've hit a wall trying to I've hit a wall trying to I'm stuck on something that should probably be simple....... While refactoring a legacy PHP application that connects to a MySQL database, I've noticed significant performance bottlenecks during peak usage times. The previous developer relied heavily on non-optimized SQL queries, which are now causing slow response times as user traffic increases. For instance, one of the functions retrieves user data from multiple tables without using joins, resulting in multiple queries being executed one after the other: ```php function getUserData($userId) { $query1 = "SELECT * FROM users WHERE id = ?"; $stmt1 = $this->db->prepare($query1); $stmt1->execute([$userId]); $user = $stmt1->fetch(); $query2 = "SELECT * FROM orders WHERE user_id = ?"; $stmt2 = $this->db->prepare($query2); $stmt2->execute([$userId]); $orders = $stmt2->fetchAll(); return [ 'user' => $user, 'orders' => $orders ]; } ``` To enhance performance, I'm considering using a single query with joins. I experimented with the following query: ```sql SELECT users.*, orders.* FROM users JOIN orders ON users.id = orders.user_id WHERE users.id = ?; ``` This approach significantly reduces the number of round trips to the database. I implemented it like this: ```php function getOptimizedUserData($userId) { $query = "SELECT users.*, orders.* FROM users JOIN orders ON users.id = orders.user_id WHERE users.id = ?"; $stmt = $this->db->prepare($query); $stmt->execute([$userId]); return $stmt->fetchAll(); } ``` Despite this improvement, I'm worried about how this change might affect existing functionality. The legacy code base has very little test coverage, so ensuring that nothing breaks is tricky. Could using prepared statements in this way introduce any security vulnerabilities, or should I consider further optimizations? Additionally, are there best practices for handling more complex queries involving multiple joins without creating performance issues? Any insights or recommendations would be appreciated! For context: I'm using Php on Ubuntu. I'd really appreciate any guidance on this. This is part of a larger application I'm building. What am I doing wrong? This is part of a larger web app I'm building. What's the best practice here? My team is using Php for this desktop app. What are your experiences with this?