Add index for source association and for path

db/migrate/20170503184421_add_index_to_redirect_routes.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+# rubocop:disable RemoveIndex
+class AddIndexToRedirectRoutes < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index(:redirect_routes, :path, unique: true)
+    add_concurrent_index(:redirect_routes, [:source_type, :source_id])
+  end
+
+  def down
+    remove_index(:redirect_routes, :path) if index_exists?(:redirect_routes, :path)
+    remove_index(:redirect_routes, [:source_type, :source_id]) if index_exists?(:redirect_routes, [:source_type, :source_id])
+  end
+end

db/schema.rb

@@ -1048,6 +1048,9 @@ ActiveRecord::Schema.define(version: 20170504102911) do
     t.datetime "updated_at", null: false
   end
 
+  add_index "redirect_routes", ["path"], name: "index_redirect_routes_on_path", unique: true, using: :btree
+  add_index "redirect_routes", ["source_type", "source_id"], name: "index_redirect_routes_on_source_type_and_source_id", using: :btree
+
   create_table "releases", force: :cascade do |t|
     t.string "tag"
     t.text "description"