diff --git a/db/schema.rb b/db/schema.rb
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -89,7 +89,7 @@
     t.index ["group_id", "problem_id"], name: "index_groups_problems_on_group_id_and_problem_id"
   end
 
-  create_table "groups_users", id: false, options: "ENGINE=InnoDB DEFAULT CHARSET=latin1", force: :cascade do |t|
+  create_table "groups_users", options: "ENGINE=InnoDB DEFAULT CHARSET=latin1", force: :cascade do |t|
     t.integer "group_id", null: false
     t.integer "user_id", null: false
     t.index ["user_id", "group_id"], name: "index_groups_users_on_user_id_and_group_id"
@@ -116,6 +116,7 @@
     t.string "ip_address"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["user_id"], name: "index_logins_on_user_id"
   end
 
   create_table "messages", id: :integer, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci", force: :cascade do |t|
@@ -215,6 +216,7 @@
     t.integer "peak_memory"
     t.integer "effective_code_length"
     t.string "ip_address"
+    t.index ["submitted_at"], name: "index_submissions_on_submitted_at"
     t.index ["user_id", "problem_id", "number"], name: "index_submissions_on_user_id_and_problem_id_and_number", unique: true
     t.index ["user_id", "problem_id"], name: "index_submissions_on_user_id_and_problem_id"
   end