Simplify AddCiRunnerGroups migration

db/migrate/20170301101006_add_ci_runner_groups.rb

@@ -5,19 +5,15 @@ class AddCiRunnerGroups < ActiveRecord::Migration
 
   disable_ddl_transaction!
 
-  def up
+  def change
     create_table :ci_runner_groups do |t|
       t.integer :runner_id
       t.integer :group_id
-    end
 
-    add_concurrent_index :ci_runner_groups, :group_id
-    add_concurrent_index :ci_runner_groups, [:runner_id, :group_id], unique: true
-    add_concurrent_foreign_key :ci_runner_groups, :ci_runners, column: :runner_id, on_delete: :cascade
-    add_concurrent_foreign_key :ci_runner_groups, :namespaces, column: :group_id, on_delete: :cascade
+      t.index [:runner_id, :group_id], unique: true
+      t.index :group_id
+      t.foreign_key :ci_runners, column: :runner_id, on_delete: :cascade
+      t.foreign_key :namespaces, column: :group_id, on_delete: :cascade
     end
-
-  def down
-    drop_table :ci_runner_groups
   end
 end

db/schema.rb

@@ -2096,8 +2096,8 @@ ActiveRecord::Schema.define(version: 20180430143705) do
   add_foreign_key "ci_pipelines", "ci_pipeline_schedules", column: "pipeline_schedule_id", name: "fk_3d34ab2e06", on_delete: :nullify
   add_foreign_key "ci_pipelines", "ci_pipelines", column: "auto_canceled_by_id", name: "fk_262d4c2d19", on_delete: :nullify
   add_foreign_key "ci_pipelines", "projects", name: "fk_86635dbd80", on_delete: :cascade
-  add_foreign_key "ci_runner_groups", "ci_runners", column: "runner_id", name: "fk_d8a0baa93b", on_delete: :cascade
-  add_foreign_key "ci_runner_groups", "namespaces", column: "group_id", name: "fk_cdafb3bbba", on_delete: :cascade
+  add_foreign_key "ci_runner_groups", "ci_runners", column: "runner_id", on_delete: :cascade
+  add_foreign_key "ci_runner_groups", "namespaces", column: "group_id", on_delete: :cascade
   add_foreign_key "ci_runner_projects", "projects", name: "fk_4478a6f1e4", on_delete: :cascade
   add_foreign_key "ci_stages", "ci_pipelines", column: "pipeline_id", name: "fk_fb57e6cc56", on_delete: :cascade
   add_foreign_key "ci_stages", "projects", name: "fk_2360681d1d", on_delete: :cascade