create_table "accounts", :force => true do |t|
  t.integer  "user_id"
  t.string   "data_key"
  t.string   "data_value"
end

belongs_to :user
DATA_KEYS = ['age', 'birthdate', 'hair_color', 'height' ] # etc..

has_many :accounts
Account::DATA_KEYS.each do |method|
  # getter method
  define_method(method) do
    accounts.find_by_data_key(method).try(:data_value)
  end

  # setter method
  define_method("#{method}=") do |value|
    data = accounts.find_or_initialize_by_data_key(method)
    data.data_value = value.strip
    data.save
  end
end

user = User.new
user.preferences = {
  email: "p@elh.mx",
  github: "heridev"
}

user.save!
user.reload

# Searching
User.where("preferences @> hstore(:key, :value)", key: "email", value: "p@elh.mx").first