Performance guide when using `includes` with large datasets in Rails 7
Can someone help me understand I'm experiencing important performance degradation when trying to load associated records using `includes` in Rails 7. My query looks something like this: ```ruby @users = User.includes(:posts).where(active: true) ``` The `users` table has around 10,000 records, and the `posts` table has about 50,000 records linked to these users. When I run this query, it takes almost 10 seconds to complete, which is unacceptable for my application. I've tried using `eager_load` instead of `includes`, but it doesn't seem to make a important difference in performance. I also verified that there are proper indexes on the `user_id` field in the `posts` table, and I'm running this in a development environment with the server running in production mode to better replicate load times. Something interesting I noticed is that if I load the users without the posts, the query runs in under a second: ```ruby @users = User.where(active: true) ``` I suspect it might be related to the way ActiveRecord is generating the SQL queries for the joins, but I haven't been able to pinpoint the scenario. Any suggestions on optimizing this or troubleshooting the slow query would be greatly appreciated. My team is using Ruby for this web app. Am I approaching this the right way?