ActiveRecord related: marginalia gem - for adding comments to ActiveRecord queries

https://signalvnoise.com/posts/3130-tech-note-mysql-query-comments-in-rails
From https://github.com/basecamp/marginalia:

Attach comments to your ActiveRecord queries. By default, it adds the application, controller, and action names as a comment at the end of each query.

This helps when searching log files for queries, and seeing where slow queries came from.

For example, once enabled, your logs will look like:

Account Load (0.3ms)  SELECT `accounts`.* FROM `accounts` 
WHERE `accounts`.`queenbee_id` = 1234567890 
LIMIT 1 
/*application:BCX,controller:project_imports,action:show*/

You can also use these query comments along with a tool like pt-query-digest to automate identification of controllers and actions that are hotspots for slow queries.

......

.......

Marginalia ships with :application, :controller, and :action enabled by default. In addition, implementation is provided for:

• :line (for file and line number calling query). :line supports a configuration by setting a regexp in Marginalia::Comment.lines_to_ignore to exclude parts of the stacktrace from inclusion in the line comment.
• :controller_with_namespace to include the full classname (including namespace) of the controller.
• :job to include the classname of the ActiveJob being performed.
• :hostname to include Socket.gethostname.
• :pid to include current process id.