Use `upsert_all` and `insert_all` to reduce back-and-forth in costly migrations (#29752)

db/migrate/20240304090449_migrate_interaction_settings_to_policy.rb

@@ -4,46 +4,50 @@ class MigrateInteractionSettingsToPolicy < ActiveRecord::Migration[7.1]
   disable_ddl_transaction!
 
   # Dummy classes, to make migration possible across version changes
-  class Account < ApplicationRecord
-    has_one :user, inverse_of: :account
-    has_one :notification_policy, inverse_of: :account
-  end
-
   class User < ApplicationRecord
-    belongs_to :account
+    belongs_to :notification_policy, foreign_key: 'account_id', primary_key: 'account_id', optional: true, inverse_of: false
   end
 
-  class NotificationPolicy < ApplicationRecord
-    belongs_to :account
-  end
+  class NotificationPolicy < ApplicationRecord; end
 
   def up
-    User.includes(account: :notification_policy).find_each do |user|
-      deserialized_settings = Oj.load(user.attributes_before_type_cast['settings'])
-
-      next if deserialized_settings.nil?
-
-      policy = user.account.notification_policy || user.account.build_notification_policy
-      requires_new_policy = false
-
-      if deserialized_settings['interactions.must_be_follower']
-        policy.filter_not_followers = true
-        requires_new_policy = true
-      end
-
-      if deserialized_settings['interactions.must_be_following']
-        policy.filter_not_following = true
-        requires_new_policy = true
-      end
-
-      unless deserialized_settings['interactions.must_be_following_dm']
-        policy.filter_private_mentions = false
-        requires_new_policy = true
-      end
-
-      policy.save if requires_new_policy && policy.changed?
+    User.includes(:notification_policy).in_batches do |users|
+      NotificationPolicy.upsert_all(users.filter_map { |user| policy_for_user(user) })
     end
   end
 
   def down; end
+
+  private
+
+  def policy_for_user(user)
+    deserialized_settings = Oj.load(user.attributes_before_type_cast['settings'])
+    return if deserialized_settings.nil?
+
+    requires_new_policy = false
+
+    policy = {
+      account_id: user.account_id,
+      filter_not_followers: false,
+      filter_not_following: false,
+      filter_private_mentions: true,
+    }
+
+    if deserialized_settings['interactions.must_be_follower']
+      policy[:filter_not_followers] = true
+      requires_new_policy = true
+    end
+
+    if deserialized_settings['interactions.must_be_following']
+      policy[:filter_not_following] = true
+      requires_new_policy = true
+    end
+
+    unless deserialized_settings['interactions.must_be_following_dm']
+      policy[:filter_private_mentions] = false
+      requires_new_policy = true
+    end
+
+    policy if requires_new_policy
+  end
 end

db/post_migrate/20240321160706_migrate_interaction_settings_to_policy_again.rb

@@ -4,51 +4,51 @@ class MigrateInteractionSettingsToPolicyAgain < ActiveRecord::Migration[7.1]
   disable_ddl_transaction!
 
   # Dummy classes, to make migration possible across version changes
-  class Account < ApplicationRecord
-    has_one :user, inverse_of: :account
-    has_one :notification_policy, inverse_of: :account
-  end
-
   class User < ApplicationRecord
-    belongs_to :account
+    belongs_to :notification_policy, foreign_key: 'account_id', primary_key: 'account_id', optional: true, inverse_of: false
   end
 
-  class NotificationPolicy < ApplicationRecord
-    belongs_to :account
-  end
+  class NotificationPolicy < ApplicationRecord; end
 
   def up
-    User.includes(account: :notification_policy).find_each do |user|
-      deserialized_settings = Oj.load(user.attributes_before_type_cast['settings'])
-
-      next if deserialized_settings.nil?
-
-      # If the user has configured a notification policy, don't override it
-      next if user.account.notification_policy.present?
-
-      policy = user.account.build_notification_policy
-      requires_new_policy = false
-
-      if deserialized_settings['interactions.must_be_follower']
-        policy.filter_not_followers = true
-        requires_new_policy = true
-      end
-
-      if deserialized_settings['interactions.must_be_following']
-        policy.filter_not_following = true
-        requires_new_policy = true
-      end
-
-      unless deserialized_settings['interactions.must_be_following_dm']
-        policy.filter_private_mentions = false
-        requires_new_policy = true
-      end
-
-      policy.save if requires_new_policy && policy.changed?
-    rescue ActiveRecord::RecordNotUnique
-      next
+    User.includes(:notification_policy).in_batches do |users|
+      NotificationPolicy.insert_all(users.filter_map { |user| policy_for_user(user) })
     end
   end
 
   def down; end
+
+  private
+
+  def policy_for_user(user)
+    deserialized_settings = Oj.load(user.attributes_before_type_cast['settings'])
+    return if deserialized_settings.nil?
+    return if user.notification_policy.present?
+
+    requires_new_policy = false
+
+    policy = {
+      account_id: user.account_id,
+      filter_not_followers: false,
+      filter_not_following: false,
+      filter_private_mentions: true,
+    }
+
+    if deserialized_settings['interactions.must_be_follower']
+      policy[:filter_not_followers] = true
+      requires_new_policy = true
+    end
+
+    if deserialized_settings['interactions.must_be_following']
+      policy[:filter_not_following] = true
+      requires_new_policy = true
+    end
+
+    unless deserialized_settings['interactions.must_be_following_dm']
+      policy[:filter_private_mentions] = false
+      requires_new_policy = true
+    end
+
+    policy if requires_new_policy
+  end
 end