DEV: Migrate notifications#id and related columns to bigint (#28584)

* DEV: Migrate notifications#id to bigint (#28444)

The `notifications.id` column is the most probable column to run out of
values. This is because it is an `int` column that has only 2147483647
values and many notifications are generated on a regular basis in an
active community. This commit migrates the column to `bigint`.

These migrations do not use `ALTER TABLE ... COLUMN ... TYPE` in order
to avoid the `ACCESS EXCLUSIVE` lock on the entire table. Instead, they
create a new `bigint` column, copy the values to the new column and
then sets the new column as primary key.

Related columns (see `user_badges`, `shelved_notifications`) will
be migrated in a follow-up commit.

* DEV: Fix bigint notifications id migration to deal with public schema (#28538)

Follow up to 799a45a291

* DEV: Migrate shelved_notifications#notification_id to bigint (#28549)

DEV: Migrate shelved_notifications#notification_id to bigint

The `notifications.id` has been migrated to `bigint` in previous commit
799a45a291.

* DEV: Fix annotations (#28569)

Follow-up to ec8ba5a0b9

* DEV: Migrate user_badges#notification_id to bigint (#28546)

The `notifications.id` has been migrated to bigint in previous commit
799a45a291. This commit migrates one of
the related columns, `user_badges.notification_id`, to `bigint`.

* DEV: Migrate `User#seen_notification_id` to `bigint` (#28572)

`Notification#id` was migrated to `bigint` in 799a45a291

* DEV: Migrate `Chat::NotificationMention#notification_id` to `bigint` (#28571)

`Notification#id` was migrated to `bigint` in 799a45a291

---------

Co-authored-by: Alan Guo Xiang Tan <gxtan1990@gmail.com>

app/models/notification.rb

@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 class Notification < ActiveRecord::Base
+  self.ignored_columns = [
+    :old_id, # TODO: Remove when column is dropped. At this point, the migration to drop the column has not been writted.
+  ]
+
   attr_accessor :acting_user
   attr_accessor :acting_username
 
@@ -407,7 +411,6 @@ end
 #
 # Table name: notifications
 #
-#  id                :integer          not null, primary key
 #  notification_type :integer          not null
 #  user_id           :integer          not null
 #  data              :string(1000)     not null
@@ -418,6 +421,7 @@ end
 #  post_number       :integer
 #  post_action_id    :integer
 #  high_priority     :boolean          default(FALSE), not null
+#  id                :bigint           not null, primary key
 #
 # Indexes
 #

app/models/shelved_notification.rb

@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 class ShelvedNotification < ActiveRecord::Base
+  self.ignored_columns = [
+    :old_notification_id, # TODO: Remove when column is dropped. At this point, the migration to drop the column has not been writted.
+  ]
+
   belongs_to :notification
 
   def process
@@ -13,7 +17,7 @@ end
 # Table name: shelved_notifications
 #
 #  id              :bigint           not null, primary key
-#  notification_id :integer          not null
+#  notification_id :bigint           not null
 #
 # Indexes
 #

app/models/user.rb

@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 class User < ActiveRecord::Base
+  self.ignored_columns = [
+    :old_seen_notification_id, # TODO: Remove when column is dropped. At this point, the migration to drop the column has not been written.
+  ]
+
   include Searchable
   include Roleable
   include HasCustomFields
@@ -2223,7 +2227,6 @@ end
 #  created_at                :datetime         not null
 #  updated_at                :datetime         not null
 #  name                      :string
-#  seen_notification_id      :integer          default(0), not null
 #  last_posted_at            :datetime
 #  password_hash             :string(64)
 #  salt                      :string(32)
@@ -2259,6 +2262,7 @@ end
 #  last_seen_reviewable_id   :integer
 #  password_algorithm        :string(64)
 #  required_fields_version   :integer
+#  seen_notification_id      :bigint           default(0), not null
 #
 # Indexes
 #

app/models/user_badge.rb

@@ -1,6 +1,10 @@
 # frozen_string_literal: true
 
 class UserBadge < ActiveRecord::Base
+  self.ignored_columns = [
+    :old_notification_id, # TODO: Remove when column is dropped. At this point, the migration to drop the column has not been writted.
+  ]
+
   belongs_to :badge
   belongs_to :user
   belongs_to :granted_by, class_name: "User"
@@ -120,11 +124,11 @@ end
 #  granted_at      :datetime         not null
 #  granted_by_id   :integer          not null
 #  post_id         :integer
-#  notification_id :integer
 #  seq             :integer          default(0), not null
 #  featured_rank   :integer
 #  created_at      :datetime         not null
 #  is_favorite     :boolean
+#  notification_id :bigint
 #
 # Indexes
 #

db/migrate/20240820123401_alter_notifications_id_sequence_to_bigint.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class AlterNotificationsIdSequenceToBigint < ActiveRecord::Migration[7.0]
+  def up
+    execute "ALTER SEQUENCE notifications_id_seq AS bigint"
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240820123402_add_big_int_notifications_id.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+class AddBigIntNotificationsId < ActiveRecord::Migration[7.0]
+  def up
+    # Short-circuit if the table has been migrated already
+    result =
+      execute(
+        "SELECT data_type FROM information_schema.columns WHERE table_name = 'notifications' AND column_name = 'id' LIMIT 1",
+      )
+    data_type = result[0]["data_type"]
+    return if data_type.downcase == "bigint"
+
+    # Create new column
+    execute "ALTER TABLE notifications ADD COLUMN new_id BIGINT NOT NULL DEFAULT 0"
+
+    # Mirror new `id` values to `new_id`
+    execute <<~SQL.squish
+      CREATE FUNCTION mirror_notifications_id()
+      RETURNS trigger AS
+      $$
+      BEGIN
+        NEW.new_id = NEW.id;
+        RETURN NEW;
+      END;
+      $$
+      LANGUAGE plpgsql
+    SQL
+
+    execute <<~SQL.squish
+      CREATE TRIGGER notifications_new_id_trigger BEFORE INSERT ON notifications
+      FOR EACH ROW EXECUTE PROCEDURE mirror_notifications_id()
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240820123403_copy_notifications_id_values.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+class CopyNotificationsIdValues < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def up
+    # Short-circuit if the table has been migrated already
+    result =
+      execute(
+        "SELECT data_type FROM information_schema.columns WHERE table_name = 'notifications' AND column_name = 'id' LIMIT 1",
+      )
+    data_type = result[0]["data_type"]
+    return if data_type.downcase == "bigint"
+
+    min_id, max_id = execute("SELECT MIN(id), MAX(id) FROM notifications")[0].values
+    batch_size = 10_000
+
+    (min_id..max_id).step(batch_size) { |start_id| execute <<~SQL } if min_id && max_id
+        UPDATE notifications
+        SET new_id = id
+        WHERE id >= #{start_id} AND id < #{start_id + batch_size} AND new_id != id
+      SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240820123404_copy_notifications_id_indexes.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+class CopyNotificationsIdIndexes < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def up
+    # Short-circuit if the table has been migrated already
+    result =
+      execute(
+        "SELECT data_type FROM information_schema.columns WHERE table_name = 'notifications' AND column_name = 'id' LIMIT 1",
+      )
+    data_type = result[0]["data_type"]
+    return if data_type.downcase == "bigint"
+
+    # Copy existing indexes and suffix them with `_bigint`
+    results =
+      execute(
+        "SELECT indexname, indexdef FROM pg_indexes WHERE tablename = 'notifications' AND indexdef SIMILAR TO '%\\mid\\M%' AND schemaname = 'public'",
+      )
+    results.each do |res|
+      indexname, indexdef = res["indexname"], res["indexdef"]
+
+      indexdef = indexdef.gsub(/\b#{indexname}\b/, "#{indexname}_bigint")
+      indexdef =
+        indexdef.gsub(
+          /\bCREATE (UNIQUE )?INDEX\b/,
+          "CREATE \\1INDEX CONCURRENTLY",
+        ) if !Rails.env.test?
+      indexdef = indexdef.gsub(/\bid\b/, "new_id")
+
+      execute "DROP INDEX #{Rails.env.test? ? "" : "CONCURRENTLY"} IF EXISTS #{indexname}_bigint"
+      execute(indexdef)
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240820123405_swap_big_int_notifications_id.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+class SwapBigIntNotificationsId < ActiveRecord::Migration[7.0]
+  def up
+    # Short-circuit if the table has been migrated already
+    result =
+      execute(
+        "SELECT data_type FROM information_schema.columns WHERE table_name = 'notifications' AND column_name = 'id' LIMIT 1",
+      )
+    data_type = result[0]["data_type"]
+    return if data_type.downcase == "bigint"
+
+    # Necessary to rename and drop columns
+    Migration::SafeMigrate.disable!
+
+    # Drop trigger and function used to replicate new values
+    execute "DROP TRIGGER notifications_new_id_trigger ON notifications"
+    execute "DROP FUNCTION mirror_notifications_id()"
+
+    # Move sequence to new column
+    execute "ALTER TABLE notifications ALTER COLUMN id DROP DEFAULT"
+    execute "ALTER TABLE notifications ALTER COLUMN new_id SET DEFAULT nextval('notifications_id_seq'::regclass)"
+    execute "ALTER SEQUENCE notifications_id_seq OWNED BY notifications.new_id"
+
+    # Swap columns
+    execute "ALTER TABLE notifications RENAME COLUMN id TO old_id"
+    execute "ALTER TABLE notifications RENAME COLUMN new_id TO id"
+
+    # Recreate primary key
+    execute "ALTER TABLE notifications DROP CONSTRAINT notifications_pkey"
+    execute "ALTER TABLE notifications ADD CONSTRAINT notifications_pkey PRIMARY KEY USING INDEX notifications_pkey_bigint"
+
+    # Keep old column and mark it as read only
+    execute "ALTER TABLE notifications ALTER COLUMN old_id DROP NOT NULL"
+    Migration::ColumnDropper.mark_readonly(:notifications, :old_id)
+  ensure
+    Migration::SafeMigrate.enable!
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240820123406_drop_old_notification_id_indexes.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+class DropOldNotificationIdIndexes < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def up
+    # Drop old indexes
+    results =
+      execute(
+        "SELECT indexname, indexdef FROM pg_indexes WHERE tablename = 'notifications' AND indexdef SIMILAR TO '%\\mold_id\\M%'",
+      )
+    results.each do |res|
+      indexname, indexdef = res["indexname"], res["indexdef"]
+      execute "DROP INDEX #{Rails.env.test? ? "" : "CONCURRENTLY"} IF EXISTS #{indexname}"
+    end
+
+    # Remove `_bigint` suffix from indexes
+    results =
+      execute(
+        "SELECT indexname, indexdef FROM pg_indexes WHERE tablename = 'notifications' AND indexdef SIMILAR TO '%\\mid\\M%' AND schemaname = 'public'",
+      )
+    results.each do |res|
+      indexname, indexdef = res["indexname"], res["indexdef"]
+      if indexname.include?("_bigint")
+        execute "ALTER INDEX #{indexname} RENAME TO #{indexname.gsub(/_bigint$/, "")}"
+      end
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240826121501_add_big_int_shelved_notifications_notification_id.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class AddBigIntShelvedNotificationsNotificationId < ActiveRecord::Migration[7.0]
+  def up
+    # Create new column
+    execute "ALTER TABLE shelved_notifications ADD COLUMN new_notification_id BIGINT NOT NULL DEFAULT 0"
+
+    # Mirror new `notification_id` values to `new_notification_id`
+    execute <<~SQL.squish
+      CREATE FUNCTION mirror_user_badges_notification_id()
+      RETURNS trigger AS
+      $$
+      BEGIN
+        NEW.new_notification_id = NEW.notification_id;
+        RETURN NEW;
+      END;
+      $$
+      LANGUAGE plpgsql
+    SQL
+
+    execute <<~SQL.squish
+      CREATE TRIGGER user_badges_new_notification_id_trigger BEFORE INSERT ON shelved_notifications
+      FOR EACH ROW EXECUTE PROCEDURE mirror_user_badges_notification_id()
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240826121502_copy_shelved_notifications_notification_id_values.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class CopyShelvedNotificationsNotificationIdValues < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def up
+    min_id, max_id = execute("SELECT MIN(id), MAX(id) FROM shelved_notifications")[0].values
+    batch_size = 10_000
+
+    (min_id..max_id).step(batch_size) { |start_id| execute <<~SQL.squish } if min_id && max_id
+        UPDATE shelved_notifications
+        SET new_notification_id = notification_id
+        WHERE id >= #{start_id} AND id < #{start_id + batch_size} AND notification_id != new_notification_id
+      SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240826121503_copy_shelved_notifications_notification_id_indexes.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class CopyShelvedNotificationsNotificationIdIndexes < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def up
+    execute "DROP INDEX #{Rails.env.test? ? "" : "CONCURRENTLY"} IF EXISTS index_shelved_notifications_on_new_notification_id"
+    execute "CREATE INDEX #{Rails.env.test? ? "" : "CONCURRENTLY"} index_shelved_notifications_on_new_notification_id ON shelved_notifications (new_notification_id)"
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240826121504_swap_big_int_shelved_notifications_notification_id.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+class SwapBigIntShelvedNotificationsNotificationId < ActiveRecord::Migration[7.0]
+  def up
+    # Necessary to rename columns and drop triggers/functions
+    Migration::SafeMigrate.disable!
+
+    # Drop trigger and function used to replicate new values
+    execute "DROP TRIGGER user_badges_new_notification_id_trigger ON shelved_notifications"
+    execute "DROP FUNCTION mirror_user_badges_notification_id()"
+
+    execute "ALTER TABLE shelved_notifications ALTER COLUMN new_notification_id DROP DEFAULT"
+
+    # Swap columns
+    execute "ALTER TABLE shelved_notifications RENAME COLUMN notification_id TO old_notification_id"
+    execute "ALTER TABLE shelved_notifications RENAME COLUMN new_notification_id TO notification_id"
+
+    # Keep old column and mark it as read only
+    execute "ALTER TABLE shelved_notifications ALTER COLUMN old_notification_id DROP NOT NULL"
+    Migration::ColumnDropper.mark_readonly(:shelved_notifications, :old_notification_id)
+
+    # Rename indexes
+    execute "DROP INDEX IF EXISTS index_shelved_notifications_on_notification_id"
+    execute "ALTER INDEX index_shelved_notifications_on_new_notification_id RENAME TO index_shelved_notifications_on_notification_id"
+  ensure
+    Migration::SafeMigrate.enable!
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240826121505_add_big_int_user_badges_notification_id.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class AddBigIntUserBadgesNotificationId < ActiveRecord::Migration[7.0]
+  def up
+    # Create new column
+    execute "ALTER TABLE user_badges ADD COLUMN new_notification_id BIGINT"
+
+    # Mirror new `notification_id` values to `new_notification_id`
+    execute <<~SQL.squish
+      CREATE FUNCTION mirror_user_badges_notification_id()
+      RETURNS trigger AS
+      $$
+      BEGIN
+        NEW.new_notification_id = NEW.notification_id;
+        RETURN NEW;
+      END;
+      $$
+      LANGUAGE plpgsql
+    SQL
+
+    execute <<~SQL.squish
+      CREATE TRIGGER user_badges_new_notification_id_trigger BEFORE INSERT ON user_badges
+      FOR EACH ROW EXECUTE PROCEDURE mirror_user_badges_notification_id()
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240826121506_copy_user_badges_notification_id_values.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class CopyUserBadgesNotificationIdValues < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+
+  def up
+    min_id, max_id = execute("SELECT MIN(id), MAX(id) FROM user_badges")[0].values
+    batch_size = 10_000
+
+    (min_id..max_id).step(batch_size) { |start_id| execute <<~SQL.squish } if min_id && max_id
+        UPDATE user_badges
+        SET new_notification_id = notification_id
+        WHERE id >= #{start_id} AND id < #{start_id + batch_size} AND notification_id IS NOT NULL AND new_notification_id IS NULL
+      SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240826121507_swap_big_int_user_badges_notification_id.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+class SwapBigIntUserBadgesNotificationId < ActiveRecord::Migration[7.0]
+  def up
+    # Necessary to rename and drop columns
+    Migration::SafeMigrate.disable!
+
+    # Drop trigger and function used to replicate new values
+    execute "DROP TRIGGER user_badges_new_notification_id_trigger ON user_badges"
+    execute "DROP FUNCTION mirror_user_badges_notification_id()"
+
+    # Swap columns
+    execute "ALTER TABLE user_badges RENAME COLUMN notification_id TO old_notification_id"
+    execute "ALTER TABLE user_badges RENAME COLUMN new_notification_id TO notification_id"
+
+    # Keep old column and mark it as read only
+    Migration::ColumnDropper.mark_readonly(:user_badges, :old_notification_id)
+  ensure
+    Migration::SafeMigrate.enable!
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240827063715_add_new_seen_notification_id_to_users.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+class AddNewSeenNotificationIdToUsers < ActiveRecord::Migration[7.1]
+  def up
+    # Create new column
+    execute "ALTER TABLE users ADD COLUMN new_seen_notification_id BIGINT NOT NULL DEFAULT(0)"
+
+    # Mirror new `seen_notification_id` values to `new_seen_notification_id`
+    execute <<~SQL.squish
+      CREATE FUNCTION mirror_users_seen_notification_id()
+      RETURNS trigger AS
+      $$
+      BEGIN
+        NEW.new_seen_notification_id = NEW.seen_notification_id;
+        RETURN NEW;
+      END;
+      $$
+      LANGUAGE plpgsql
+    SQL
+
+    execute <<~SQL.squish
+      CREATE TRIGGER users_seen_notification_id_trigger BEFORE INSERT OR UPDATE ON users
+      FOR EACH ROW EXECUTE PROCEDURE mirror_users_seen_notification_id()
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240827063908_copy_users_seen_notification_id_values.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+class CopyUsersSeenNotificationIdValues < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def up
+    min_id, max_id = execute("SELECT MIN(id), MAX(id) FROM users")[0].values
+    batch_size = 10_000
+
+    (min_id..max_id).step(batch_size) { |start_id| execute <<~SQL.squish } if min_id && max_id
+        UPDATE users
+        SET new_seen_notification_id = seen_notification_id
+        WHERE id >= #{start_id} AND id < #{start_id + batch_size} AND new_seen_notification_id != seen_notification_id
+      SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20240827064121_swap_seen_notification_id_with_seen_notification_id_on_users.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+class SwapSeenNotificationIdWithSeenNotificationIdOnUsers < ActiveRecord::Migration[7.1]
+  def up
+    # Necessary to rename and drop columns
+    Migration::SafeMigrate.disable!
+
+    # Drop trigger and function used to replicate new values
+    execute "DROP TRIGGER users_seen_notification_id_trigger ON users"
+    execute "DROP FUNCTION mirror_users_seen_notification_id()"
+
+    # Swap columns
+    execute "ALTER TABLE users RENAME COLUMN seen_notification_id TO old_seen_notification_id"
+    execute "ALTER TABLE users RENAME COLUMN new_seen_notification_id TO seen_notification_id"
+    execute "ALTER TABLE users ALTER COLUMN old_seen_notification_id DROP NOT NULL"
+    execute "ALTER TABLE users ALTER COLUMN old_seen_notification_id DROP DEFAULT"
+
+    # Keep old column and mark it as read only
+    Migration::ColumnDropper.mark_readonly(:users, :old_seen_notification_id)
+  ensure
+    Migration::SafeMigrate.enable!
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

lib/tasks/db.rake

@@ -259,7 +259,12 @@ task "db:migrate" => %w[
     ActiveRecord::Tasks::DatabaseTasks.migrate
 
     SeedFu.quiet = true
+
+    begin
       SeedFu.seed(SeedHelper.paths, SeedHelper.filter)
+    rescue => error
+      error.backtrace.each { |l| puts l }
+    end
 
     Rake::Task["db:schema:cache:dump"].invoke if Rails.env.development? && !ENV["RAILS_DB"]
 

plugins/chat/app/models/chat/mention_notification.rb

@@ -4,6 +4,10 @@ module Chat
   class MentionNotification < ActiveRecord::Base
     self.table_name = "chat_mention_notifications"
 
+    self.ignored_columns = [
+      :old_notification_id, # TODO remove once this column is removed. Migration to drop the column has not been written.
+    ]
+
     belongs_to :chat_mention, class_name: "Chat::Mention"
     belongs_to :notification, dependent: :destroy
   end
@@ -14,7 +18,7 @@ end
 # Table name: chat_mention_notifications
 #
 #  chat_mention_id :integer          not null
-#  notification_id    :integer    not null
+#  notification_id :bigint           not null
 #
 # Indexes
 #

plugins/chat/db/migrate/20240827040131_add_new_notification_id_to_chat_mention_notifications.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+class AddNewNotificationIdToChatMentionNotifications < ActiveRecord::Migration[7.1]
+  def up
+    # Create new column
+    execute "ALTER TABLE chat_mention_notifications ADD COLUMN new_notification_id BIGINT NOT NULL DEFAULT(0)"
+
+    # Mirror new `notification_id` values to `new_notification_id`
+    execute(<<~SQL)
+      CREATE FUNCTION mirror_chat_mention_notifications_notification_id()
+      RETURNS trigger AS
+      $$
+      BEGIN
+        NEW.new_notification_id = NEW.notification_id;
+        RETURN NEW;
+      END;
+      $$
+      LANGUAGE plpgsql
+    SQL
+
+    execute(<<~SQL)
+      CREATE TRIGGER chat_mention_notifications_new_notification_id_trigger BEFORE INSERT ON chat_mention_notifications
+      FOR EACH ROW EXECUTE PROCEDURE mirror_chat_mention_notifications_notification_id()
+    SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

plugins/chat/db/migrate/20240827040550_copy_chat_mention_notifications_notification_id_values.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+class CopyChatMentionNotificationsNotificationIdValues < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def up
+    min_id, max_id =
+      execute("SELECT MIN(notification_id), MAX(notification_id) FROM chat_mention_notifications")[
+        0
+      ].values
+    batch_size = 10_000
+
+    (min_id..max_id).step(batch_size) { |start_id| execute <<~SQL.squish } if min_id && max_id
+        UPDATE chat_mention_notifications
+        SET new_notification_id = notification_id
+        WHERE notification_id >= #{start_id} AND notification_id < #{start_id + batch_size} AND new_notification_id != notification_id
+      SQL
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

plugins/chat/db/migrate/20240827040810_copy_chat_mention_notifications_notification_id_indexes.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+class CopyChatMentionNotificationsNotificationIdIndexes < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def up
+    execute "DROP INDEX #{Rails.env.test? ? "" : "CONCURRENTLY "} IF EXISTS index_chat_mention_notifications_on_new_notification_id"
+    execute "CREATE UNIQUE INDEX #{Rails.env.test? ? "" : "CONCURRENTLY "} index_chat_mention_notifications_on_new_notification_id ON chat_mention_notifications (new_notification_id)"
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

plugins/chat/db/migrate/20240827040811_swap_bigint_chat_mention_notifications_notification_id.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+class SwapBigintChatMentionNotificationsNotificationId < ActiveRecord::Migration[7.1]
+  def up
+    # Necessary to rename and drop trigger/function
+    Migration::SafeMigrate.disable!
+
+    # Drop trigger and function used to replicate new values
+    execute "DROP TRIGGER chat_mention_notifications_new_notification_id_trigger ON chat_mention_notifications"
+    execute "DROP FUNCTION mirror_chat_mention_notifications_notification_id()"
+
+    # Swap columns
+    execute "ALTER TABLE chat_mention_notifications RENAME COLUMN notification_id TO old_notification_id"
+    execute "ALTER TABLE chat_mention_notifications RENAME COLUMN new_notification_id TO notification_id"
+
+    # Drop old indexes
+    execute "DROP INDEX index_chat_mention_notifications_on_notification_id"
+    execute "ALTER INDEX index_chat_mention_notifications_on_new_notification_id RENAME TO index_chat_mention_notifications_on_notification_id"
+
+    execute "ALTER TABLE chat_mention_notifications ALTER COLUMN old_notification_id DROP NOT NULL"
+    execute "ALTER TABLE chat_mention_notifications ALTER COLUMN notification_id DROP DEFAULT"
+
+    # Keep old column and mark it as read only
+    Migration::ColumnDropper.mark_readonly(:chat_mention_notifications, :old_notification_id)
+  ensure
+    Migration::SafeMigrate.enable!
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end