UniqueValidationInspector

A Rake task that helps you find unique validations in models that do not have proper DB indexes.

If uniqueness validation is enabled, Rails will look for existing records before performing Model.create, Model.save, Model.update ... operations. If a record was found the validation fails and the transaction will be rolled back, if not the record will be saved.

For example, you have User model and uniqueness validation for facebook_id field. The following SQL query will be performed on validation:

 SELECT  1 AS one FROM `users` WHERE (`users`.`facebook_id ` = 1523123128921623) LIMIT 1

If you do not have DB index for facebook_id field then your Model.create, Model.save, Model.update ... operations will be slower and slower with user base grow.

So this gem is here to notify you about it.

Read Rails: make sure you have proper DB indexes for your model’s unique validations article to understand what kind of performance issues you may have without proper indexes.

Also read How I Reduced my DB Server Load by 80% article.

Supported versions

Ruby 1.8.7, 1.9.2, 1.9.3, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5
Rails 3.0.x, 3.1.x, 3.2.x, 4.0.x, 4.1.x, 5.0.x, 5.1.x, 5.2.x

Installation

Add this line to your application's Gemfile:

gem 'unique_validation_inspector'

And then execute:

$ bundle

Or install it yourself as:

$ gem install unique_validation_inspector

Usage

Just run the following command in your Rails app directory:

$ rake inspect_unique_validations

Output

You have the following unique validations:

Model 'Application':
[:title] (scope 'account_id'). Index exists: false

Model 'User':
[:email] (scope 'application_id'). Index exists: true
[:login] (scope 'application_id'). Index exists: false
[:facebook_id] (scope 'application_id'). Index exists: true
[:twitter_id] (scope 'application_id'). Index exists: false
[:external_user_id] (scope 'application_id'). Index exists: false
[:blob_id]. Index exists: true

All things with Index exists: false are problematic and you should fix it by adding proper DB indexes.

Consider use one of the following solutions to resolve above issues:

Add proper DB index.
Move unique validation to DB level. More info in the article https://medium.com/@igorkhomenko/rails-make-sure-you-have-proper-db-indexes-for-your-models-unique-validations-ffd0364df26f