Archive for January 27, 2016

• Unit Testing ActiveRecord eager-loading

  January 27, 2016

  If you’ve worked with relational databases and any ORMs like Java’s Hibernate, .NET’s NHibernate or Rails’ ActiveRecord in the past, you might be familiar with SELECT N+1 issues. It is a common performance problem in database-dependent applications and, because of this, these ORMs provide a built-in solution to this problem.

  In ActiveRecord, includes, preload and eager_load come to the rescue. Therefore, it is not unusual to find these keywords scattered in different places where your application accesses the database. Hopefully this isn’t a lot of places though - you are using Query Objects, right?

  An example application

  Let’s imagine for a second that we have an application where you can browse restaurants, which in turn have many reviews…

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