Add unique index on parks#code

db/migrate/20251008044109_create_parks.rb

@@ -8,5 +8,7 @@ class CreateParks < ActiveRecord::Migration[8.0]
 
       t.timestamps
     end
+
+    add_index :parks, :code, unique: true
   end
 end

db/schema.rb

@@ -18,5 +18,6 @@ ActiveRecord::Schema[8.0].define(version: 2025_10_08_044109) do
     t.json "properties", default: {}, null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
+    t.index ["code"], name: "index_parks_on_code", unique: true
   end
 end