RailsQueryTracer

RailsQueryTracer hooks into ActiveRecord and helps you detect N+1 queries and slow queries in your Rails applications. It provides actionable insights and can optionally be integrated into a dashboard.

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Installation

Add this line to your application's Gemfile:

gem "rails-query-tracer", "~> 0.1.0"

Then execute:

bundle install

Or install it manually:

gem install rails-query-tracer

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Usage

Configuration

You can customize RailsQueryTracer's behavior by setting options in an initializer (config/initializers/rails_query_tracer.rb):

RailsQueryTracer::Config.slow_queries_threshold = 50   # default is 20ms
RailsQueryTracer::Config.show_stack_trace = true       # default is true
RailsQueryTracer::Config.log_to_file = "log/query_tracer.log" # optional

Tracking Queries

Start tracking SQL queries anywhere in your application (typically in a Rails initializer or a before hook):

RailsQueryTracer::Tracker.reset!
RailsQueryTracer::Tracker.start

Stop tracking if needed:

RailsQueryTracer::Tracker.stop

Access the collected queries:

queries = RailsQueryTracer::Tracker.queries

Analyzing Queries

Analyze tracked queries to detect N+1 or slow queries:

report = RailsQueryTracer::Analyzer.analyze(queries)

• report[:n_plus_one] → array of detected N+1 queries
• report[:slow] → array of slow queries exceeding RailsQueryTracer::Config.slow_queries_threshold (default 20ms)

Reporting

Print a human-readable report:

RailsQueryTracer::Reporter.report(report)

Sample output:

[RailsQueryTracer] N+1 Queries:
  SELECT * FROM users repeated 5 times at app/models/post.rb:12

[RailsQueryTracer] Slow Queries:
  SELECT * FROM orders (250.32ms) at app/controllers/orders_controller.rb:45

[RailsQueryTracer] Report Complete

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Tips & Best Practices

• Reset Tracker before each request in development to avoid mixing queries from different actions.
• Ignore schema queries automatically—RailsQueryTracer ignores SCHEMA queries by default.
• Combine with bullet for automated notifications in development if you want live alerts.
• Adjust slow query threshold via RailsQueryTracer::Config.slow_queries_threshold.
• Avoid running in production unless you specifically need performance diagnostics, as it collects all queries in memory.

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Contributing

1. Fork it (https://github.com/your-username/rails-query-tracer/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

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License

MIT License