Create foreign keys for pipeline stages in migration

db/post_migrate/20170526190708_create_foreign_keys_for_pipeline_stages.rb

+class CreateForeignKeysForPipelineStages < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_foreign_key :ci_stages, :projects, column: :project_id, on_delete: :cascade
+    add_concurrent_foreign_key :ci_builds, :ci_stages, column: :stage_id, on_delete: :cascade
+  end
+
+  def down
+    remove_foreign_key :ci_stages, column: :project_id
+    remove_foreign_key :ci_builds, column: :stage_id
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170526185921) do
+ActiveRecord::Schema.define(version: 20170526190708) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1429,10 +1429,12 @@ ActiveRecord::Schema.define(version: 20170526185921) do
   add_foreign_key "boards", "projects"
   add_foreign_key "chat_teams", "namespaces", on_delete: :cascade
   add_foreign_key "ci_builds", "ci_pipelines", column: "auto_canceled_by_id", name: "fk_a2141b1522", on_delete: :nullify
+  add_foreign_key "ci_builds", "ci_stages", column: "stage_id", name: "fk_3a9eaa254d", on_delete: :cascade
   add_foreign_key "ci_pipeline_schedules", "projects", name: "fk_8ead60fcc4", on_delete: :cascade
   add_foreign_key "ci_pipeline_schedules", "users", column: "owner_id", name: "fk_9ea99f58d2", on_delete: :nullify
   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_stages", "projects", name: "fk_2360681d1d", on_delete: :cascade
   add_foreign_key "ci_trigger_requests", "ci_triggers", column: "trigger_id", name: "fk_b8ec8b7245", on_delete: :cascade
   add_foreign_key "ci_triggers", "users", column: "owner_id", name: "fk_e8e10d1964", on_delete: :cascade
   add_foreign_key "ci_variables", "projects", name: "fk_ada5eb64b3", on_delete: :cascade