How to optimize query performance with eager loading in Rails 7 for complex associations?
I'm deploying to production and I'm optimizing some code but I'm testing a new approach and I'm experimenting with I'm reviewing some code and Hey everyone, I'm running into an issue that's driving me crazy... I'm working on a Rails 7 application where I have a `Post` model that has many `Comments` and each `Comment` belongs to a `User`. The scenario arises when I attempt to load posts along with their comments and user data for displaying in my view. The query performance is abysmally slow, especially when I have a large number of posts. I tried using `includes` for eager loading, but I still encounter N+1 query problems and the performance doesn't seem to improve significantly. Here’s what I have so far: ```ruby # In my PostsController class PostsController < ApplicationController def index @posts = Post.includes(comments: :user).all end end ``` However, when I check the log, I still see multiple queries being executed, especially when accessing the comments and the associated user data in my view: ```erb <% @posts.each do |post| %> <h2><%= post.title %></h2> <% post.comments.each do |comment| %> <p><%= comment.body %> by <%= comment.user.name %></p> <% end %> <% end %> ``` Despite using `includes`, it appears that Rails is still running multiple queries for comments and users. I've also tried using `joins` instead of `includes`, but that didn't help either. I’m now getting this behavior when I use joins: ``` ActiveRecord::StatementInvalid (PG::UndefinedTable: behavior: relation "comments" does not exist) ``` I’m not sure if I’m missing something in how I structure my queries or if there’s a better approach to optimize this for performance. Are there best practices or specific techniques for handling complex associations in Rails 7? Any guidance would be appreciated. For context: I'm using Ruby on Linux. Is there a better approach? I'm working with Ruby in a Docker container on Ubuntu 20.04. Am I missing something obvious? I'm working with Ruby in a Docker container on Windows 10. Any help would be greatly appreciated! This is part of a larger desktop app I'm building. What are your experiences with this?