High Performance PostgreSQL for Rails

Tooling to Find Problematic Query Patterns

While manual checks are useful, the Rails ecosystem has many gems and tools to detect N+1 queries. These tools could be integrated into your development flow to add some automation.

The Ruby gem Prosopite^[124] is an N+1 detection gem that’s been added to Rideshare, along with pg_query,^[125] which it depends on.

Let’s see if Prosopite picks up this deliberate N+1. Run the code again in Rideshare from bin/rails console inside of a Prosopite block, as this shows. Set Prosopite.rails_logger = true.

ruby/n_plus_one_detection.rb

Prosopite.rails_logger = true

Prosopite.scan do
  Vehicle.all.each do |vehicle|
    vehicle.vehicle_reservations.count
  end
end

Hopefully, you saw that Prosopite ...