The In-depth Guide to ActiveRecord load_async in Rails 7

Rails 7 introduces ActiveRecord load_async API that runs SQL queries asynchronously in the background thread. This seemingly simple change of just adding a single new method that takes no arguments has profound implications for database layer interactions. In this tutorial, we’ll deep dive into the intricacies of this new API. We’ll discuss lazy-loaded queries, Ruby threading model, blocking IO, database pool vs. max connections limit, and performance impact of concurrent database clients. I’ll also try to suggest scenarios where introducing async SQL queries could have the most benefit without sacrificing the stability of your Rails app.