Append to self.ignored_columns instead of setting

app/models/application_setting.rb

@@ -31,7 +31,7 @@ class ApplicationSetting < ApplicationRecord
   serialize :repository_storages # rubocop:disable Cop/ActiveRecordSerialize
   serialize :asset_proxy_whitelist, Array # rubocop:disable Cop/ActiveRecordSerialize
 
-  self.ignored_columns = %i[
+  self.ignored_columns += %i[
                          clientside_sentry_dsn
                          clientside_sentry_enabled
                          koding_enabled

app/models/ci/build.rb

@@ -17,7 +17,7 @@ module Ci
 
     BuildArchivedError = Class.new(StandardError)
 
-    self.ignored_columns = %i[
+    self.ignored_columns += %i[
                            artifacts_file
                            artifacts_file_store
                            artifacts_metadata

app/models/ci/runner.rb

@@ -35,7 +35,7 @@ module Ci
 
     FORM_EDITABLE = %i[description tag_list active run_untagged locked access_level maximum_timeout_human_readable].freeze
 
-    self.ignored_columns = %i[is_shared]
+    self.ignored_columns += %i[is_shared]
 
     has_many :builds
     has_many :runner_projects, inverse_of: :runner, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent

app/models/deploy_key.rb

@@ -10,7 +10,7 @@ class DeployKey < Key
   scope :are_public,  -> { where(public: true) }
   scope :with_projects, -> { includes(deploy_keys_projects: { project: [:route, :namespace] }) }
 
-  self.ignored_columns = %i[can_push]
+  self.ignored_columns += %i[can_push]
 
   accepts_nested_attributes_for :deploy_keys_projects
 

app/models/note.rb

@@ -33,7 +33,7 @@ class Note < ApplicationRecord
     end
   end
 
-  self.ignored_columns = %i[original_discussion_id]
+  self.ignored_columns += %i[original_discussion_id]
 
   cache_markdown_field :note, pipeline: :note, issuable_state_filter_enabled: true
 

app/models/notification_setting.rb

 # frozen_string_literal: true
 
 class NotificationSetting < ApplicationRecord
-  self.ignored_columns = %i[events]
+  self.ignored_columns += %i[events]
 
   enum level: { global: 3, watch: 2, participating: 1, mention: 4, disabled: 0, custom: 5 }
 

app/models/user.rb

@@ -23,7 +23,7 @@ class User < ApplicationRecord
 
   DEFAULT_NOTIFICATION_LEVEL = :participating
 
-  self.ignored_columns = %i[
+  self.ignored_columns += %i[
                          authentication_token
                          email_provider
                          external_email

doc/development/what_requires_downtime.md

@@ -50,7 +50,7 @@ places. This can be done by defining the columns to ignore. For example, to igno
 
 ```ruby
 class User < ApplicationRecord
-  self.ignored_columns = %i[updated_at]
+  self.ignored_columns += %i[updated_at]
 end
 ```
 

ee/app/models/ee/application_setting.rb

@@ -14,7 +14,7 @@ module EE
 
       belongs_to :file_template_project, class_name: "Project"
 
-      self.ignored_columns = %i[minimum_mirror_sync_time]
+      self.ignored_columns += %i[minimum_mirror_sync_time]
 
       validates :shared_runners_minutes,
                 numericality: { greater_than_or_equal_to: 0 }

ee/app/models/ee/project.rb

@@ -21,7 +21,7 @@ module EE
       include InsightsFeature
       include Vulnerable
 
-      self.ignored_columns = %i[
+      self.ignored_columns += %i[
         mirror_last_update_at
         mirror_last_successful_update_at
         next_execution_timestamp

ee/app/models/ee/project_import_state.rb

@@ -6,7 +6,7 @@ module EE
     extend ::Gitlab::Utils::Override
 
     prepended do
-      self.ignored_columns = %i[created_at updated_at]
+      self.ignored_columns += %i[created_at updated_at]
 
       BACKOFF_PERIOD = 24.seconds
       JITTER = 6.seconds

ee/app/models/ee/user.rb

@@ -18,7 +18,7 @@ module EE
     prepended do
       EMAIL_OPT_IN_SOURCE_ID_GITLAB_COM = 1
 
-      self.ignored_columns = %i[support_bot]
+      self.ignored_columns += %i[support_bot]
 
       # We aren't using the `auditor?` method for the `if` condition here
       # because `auditor?` returns `false` when the `auditor` column is `true`

ee/app/models/project_repository_state.rb

@@ -3,7 +3,7 @@
 class ProjectRepositoryState < ApplicationRecord
   include ShaAttribute
 
-  self.ignored_columns = %i[last_repository_verification_failed last_wiki_verification_failed]
+  self.ignored_columns += %i[last_repository_verification_failed last_wiki_verification_failed]
 
   sha_attribute :repository_verification_checksum
   sha_attribute :wiki_verification_checksum