Which is more efficient while creating records with unique values for a column in rails Placing uniqueness validation vs finding if record exists with same value and create based on the existence.
Which is more efficient in terms of coding and performance.
A database uniqueness constraint will give you the highest performance.
At the application level, whether you are using validates_uniqueness_of or manually finding if the record exists, the performance will basically be the same. In fact, that is exactly how it is implemented in Rails: https://github.com/rails/rails/blob/0d73d6e7b6dd1900f105397460b777ef6c03d3b6/activerecord/lib/active_record/validations/uniqueness.rb#L33