Give the backtrace for all the SQL query performed in development mode. (into config/initializers/)

active_record_log_subscriber.rb

unless Rails.env.production?
  module LogQuerySources

    LOG_QUERY_LINES = ENV.fetch('LOG_QUERY_LINES', 3).to_i

    def debug(*args, &block)
      return unless super

      backtrace = Rails.backtrace_cleaner.clean(caller)

      backtrace.take(LOG_QUERY_LINES).each do |caller_line|
        next if caller_line.include?('/initializers/active_record_log_subscriber/')
        logger.debug("  ↳ #{ caller_line.sub("#{ Rails.root }/", '') }")
      end
      if (missing_row_count = (backtrace.count - LOG_QUERY_LINES)) > 0
        if missing_row_count > 1
          logger.debug("  ↳ ... (There's #{missing_row_count} more rows available. Please change LOG_QUERY_LINES if you want more.)")
        end
        logger.debug("  ↳ #{ backtrace.last.sub("#{ Rails.root }/", '') }")
      end
    end
  end
  ActiveRecord::LogSubscriber.send :prepend, LogQuerySources
end

Adding other services (Solr, redis, & other) : https://gist.github.com/mnutt/566725