All migration files in Rails are by default prefixed with the timestamp which serves as the version number for the migration file. For an instance a migration file with name 20160310141700_create_users.rb is prefixed with timestamp 20160310141700.

Rails 5 introduced ArrayInquirer as a new member to Inquirer family which initially consisted of well known StringInquirer.

Database is considered an expensive resource, and while developing our application we should be particular about the number of DB queries made, in general fewer the DB queries executed, the better the performance.