Use bigserial for internal_ids table.

db/migrate/20180305095250_create_internal_ids_table.rb

@@ -6,7 +6,7 @@ class CreateInternalIdsTable < ActiveRecord::Migration
   disable_ddl_transaction!
 
   def up
-    create_table :internal_ids do |t|
+    create_table :internal_ids, id: :bigserial do |t|
       t.references :project
       t.integer :usage, null: false
       t.integer :last_value, null: false

db/schema.rb

@@ -866,7 +866,7 @@ ActiveRecord::Schema.define(version: 20180309160427) do
 
   add_index "identities", ["user_id"], name: "index_identities_on_user_id", using: :btree
 
-  create_table "internal_ids", force: :cascade do |t|
+  create_table "internal_ids", id: :bigserial, force: :cascade do |t|
     t.integer "project_id"
     t.integer "usage", null: false
     t.integer "last_value", null: false