Add missing unique indexes to notifications (#8273)

.rubocop_todo.yml

@@ -82,7 +82,6 @@ Rails/UniqueValidationWithoutIndex:
     - 'app/models/article.rb'
     - 'app/models/comment.rb'
     - 'app/models/follow.rb'
-    - 'app/models/notification.rb'
     - 'app/models/broadcast.rb'
 
 # Offense count: 33

db/migrate/20200604133925_add_unique_index_to_notifications_user_id_organization_id_notifiable_action.rb

@@ -0,0 +1,19 @@
+class AddUniqueIndexToNotificationsUserIdOrganizationIdNotifiableAction < ActiveRecord::Migration[6.0]
+  disable_ddl_transaction!
+
+  def change
+    return if index_exists?(
+      :notifications,
+      %i[user_id organization_id notifiable_id notifiable_type action],
+      name: :index_notifications_user_id_organization_id_notifiable_action
+    )
+
+    add_index(
+      :notifications,
+      %i[user_id organization_id notifiable_id notifiable_type action],
+      unique: true,
+      algorithm: :concurrently,
+      name: :index_notifications_user_id_organization_id_notifiable_action
+    )
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_06_02_174329) do
+ActiveRecord::Schema.define(version: 2020_06_04_133925) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -683,6 +683,7 @@ ActiveRecord::Schema.define(version: 2020_06_02_174329) do
     t.index ["organization_id"], name: "index_notifications_on_organization_id"
     t.index ["user_id", "notifiable_id", "notifiable_type", "action"], name: "index_notifications_on_user_notifiable_and_action_not_null", unique: true, where: "(action IS NOT NULL)"
     t.index ["user_id", "notifiable_id", "notifiable_type"], name: "index_notifications_on_user_notifiable_action_is_null", unique: true, where: "(action IS NULL)"
+    t.index ["user_id", "organization_id", "notifiable_id", "notifiable_type", "action"], name: "index_notifications_user_id_organization_id_notifiable_action", unique: true
     t.index ["user_id"], name: "index_notifications_on_user_id"
   end