👀 Views: 0 💬 Answers: 1 📅 Created: 2025-09-07

ruby-on-rails activerecord performance Ruby

I've tried everything I can think of but I'm working on a project and hit a roadblock... I've been struggling with this for a few days now and could really use some help. During development of a Rails 7.1 application, I noticed significant performance lags when fetching related data from complex ActiveRecord associations. The app includes nested resources and, in several cases, queries that utilize `includes` to avoid N+1 queries are still slower than expected. I’ve been trying to dig into the query plans and found that some of my joins are resulting in Cartesian products, which I suspect might be due to how I set up the associations. For example, I have a `Post` model that has many `Comments`, and each `Comment` has a `User`. My initial query looks something like this: ```ruby Post.includes(:comments => :user).where('posts.published = ?', true) ``` While this should theoretically optimize the query, profiling shows it’s still pulling in too many records, especially when a post has a large number of comments. I even tried using `.references(:comments)` and `.distinct` to limit the result set but didn’t see much improvement. In my last attempt, I switched to using a raw SQL query to gain more control over the selects but ran into issues with ActiveRecord not mapping the attributes correctly. Here’s what my SQL looked like: ```sql SELECT posts.*, comments.*, users.* FROM posts JOIN comments ON comments.post_id = posts.id JOIN users ON users.id = comments.user_id WHERE posts.published = true; ``` This worked, but manually handling the results is cumbersome, and I’d rather leverage ActiveRecord’s features. Community recommendations suggest examining the database indices on foreign key columns, which I’ve confirmed are in place but may not be optimized. I also explored using the `eager_load` method, which combines the benefits of both `includes` and direct SQL querying, but the performance was still not where I expected it to be. Any insights on optimizing such complex ActiveRecord queries without sacrificing maintainability would be highly appreciated. I'm working on a service that needs to handle this. Has anyone else encountered this? This is happening in both development and production on Debian. The project is a application built with Ruby.