This is not so much a feature as a way to let developers know that they may accidentally impact the application's performance negatively if they switch primary key to non-indexed columns. By default Rails creates an index for the primary key column (id). If the developer switches (via id: false) in migration or self.primary_key = column_name in model, it will be helpful to let them know that their current primary key isn't indexed.
-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-core+unsubscr...@googlegroups.com. To post to this group, send email to rubyonrails-core@googlegroups.com. Visit this group at https://groups.google.com/group/rubyonrails-core. For more options, visit https://groups.google.com/d/optout.
