```ruby
class AddLighthouseSampleCogUkIdIndex < ActiveRecord::Migration[6.0]
  def change
    change_table :lighthouse_sample, bulk: true do |t|
      t.index :cog_uk_id
    end
  end
end
```

Add index for cog uk id
user
```ruby
# frozen_string_literal: true

#
# Add index for cog uk id
class AddLighthouseSampleCogUkIdIndex < ActiveRecord::Migration[6.0]
  def change
    change_table :lighthouse_sample, bulk: true do |t|
      t.index :cog_uk_id
    end
  end
end
```
assistant