SQL Probe

SQL Probe is a tool to trace SQL utilization in your application and provides a UI investigate how tables are accessed.

The tools is useful for discovering:

• N+1 queries
• unexpected inserts, updates and deletes
• overloaded controller actions
• most frequently accessed tables

Setup

To get started, include our action listener to the top most controller in your Rails application.

class ApplicationController < ActionController::Base 
  include SqlProbe::RequestListener
end

This effectively sets up an around_action which registers an ActiveSupport::Notification listener for 'sql.active_record' and starts writing structured SQL logs to disk associated with request data. The data is stored at SqlProbe.output_base_dir which defaults to tmp/sql_probe.

Next step is to mount the engine to engine to your application.

# config/routes.rb
mount SqlProbe::Engine => '/sql_probe'

Probing the SQL

Restart your application and go to http://localhost:3000/sql_probe. By default listening is not enabled. Click the "Start Listening" button located at the upper right to start listening.

Open a new browser window and poke around your application. To generate some SQL logs. Then return to /sql_probe to see the summary information. From this point feel free to click around the UI. Help panels are in the UI to guide you through the process.