ColumnsTrace

Detects unnecessary selected database columns in Rails controllers, ActiveJob and Sidekiq jobs.

Requirements

ruby 2.7+
rails 6.0+

Installation

Add this line to your application's Gemfile:

gem 'columns_trace'

And then run:

$ bundle install

Usage

Hit a controller or email action or run ActiveJob (or Sidekiq) job, open log/columns_trace.log, and see the output:

ImportsController#create
  1 User record: unused columns - "bio", "settings"; used columns - "id", "email", "name",
  "account_id", "created_at", "updated_at"
  ↳ app/controllers/application_controller.rb:32:in `block in <class:ApplicationController>'

  1 Account record: unused columns - "settings", "logo", "updated_at";
  used columns - "id", "plan_id"
  ↳ app/controllers/application_controller.rb:33:in `block in <class:ApplicationController>'

  10 Project records: unused columns - "description", "avatar", "url", "created_at", "updated_at";
  used columns - "id", "user_id"
  ↳ app/models/user.rb:46: in `projects'
    app/services/imports_service.rb:129: in `import_projects'
    app/controllers/imports_controller.rb:49:in `index'

ImportProjectJob
  1 User record: unused columns - "email", "name", "bio", "created_at", "updated_at";
  used columns - "id", "settings"
  ↳ app/jobs/import_project_job.rb:23:in `perform'

  1 Project record: unused columns - "description", "avatar", "settings", "created_at",
  "updated_at"; used columns - "id", "user_id", "url"
  ↳ app/jobs/import_project_job.rb:24:in `perform'

Tracing custom code

To get columns usage in the custom code, you can manually wrap it by ColumnsTrace.report:

task my_rake_task: :environment do
  ColumnsTrace.report("my_rake_task") do
    # do stuff
  end
end

Configuration

You can override the following default options:

# config/initializers/columns_trace.rb

ColumnsTrace.configure do |config|
  # Configures models that will be ignored.
  # Always adds Rails' internal `ActiveRecord::SchemaMigration`
  # and `ActiveRecord::InternalMetadata` models by default.
  config.ignored_models = []

  # Configures columns that will be ignored.
  #
  # Global setting
  #   config.ignored_columns = [:updated_at]
  # Per-model setting
  #   config.ignored_columns = [:updated_at, { User => :admin }]
  config.ignored_columns = []

  # The reporter that is used for reporting.
  # Defaults to log reporter that outputs to `log/columns_trace.log` file
  # when inside a Rails application.
  config.reporter = nil

  # Controls the contents of the printed backtrace.
  # Is set to the default Rails.backtrace_cleaner when the gem is used in the Rails app.
  config.backtrace_cleaner = ->(backtrace) { backtrace }
end

Sidekiq integration is disabled by default. You need to explicitly enable it:

# config/initializers/columns_trace.rb

ColumnsTrace.enable_sidekiq_tracing!

Custom reporters

By default offenses are reported to a log reporter that outputs to log/columns_trace.log file when inside a Rails application.

You can set your custom reporter by defining a class responding to #report method.

class MyReporter
  def report(title, created_records)
    title # => "controller#action"
    created_records # => [#<ColumnsTrace::CreatedRecord>]
    created_records.each do |record|
      record.model # class of ActiveRecord model
      record.accessed_fields  # array of accessed fields
      record.unused_fields # array of unused fields
      record.backtrace # array of strings
      record.record # ActiveRecord model instance
    end
  end
end

ColumnsTrace.reporter = MyReporter.new

Development

After checking out the repo, run bundle install to install dependencies. Then, run rake to run the linter and tests.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Additional resources

Alternatives:

snip_snip - archived, supports only controllers

Interesting reads:

Reasons why SELECT * is bad for SQL performance

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/fatkodima/columns_trace.

License

The gem is available as open source under the terms of the MIT License.

columns_trace

Runtime