Transcript:
Hello and welcome to the first OmbuCast by OmbuLabs. In this screencast we’ll
be taking a look at the
derailed_benchmarks gem,
and how you can use it to benchmark your Rails application and find, and
hopefully fix bottlenecks in your code.
When working on a Rails project, you may have seen present? calls on
ActiveRecord relationships. This might feel natural, mostly because present?
exists on all objects via ActiveSupport, so you expect the relationship to respond to it,
but it’s actually not a very good idea. If all we want to do is check if the
scope returns any results from the database, there are better ways than using
present?.
Often, Enumerable#select is the chosen method to obtain elements from an
Array for a given block. Without thinking twice, we may be doing more work than
necessary by not taking advantage of another method from the Enumerable module,
Enumerable#grep.