Schema for user_vouchers:
- id (integer)
- user_id (integer)
- voucher_id (integer)
- assigned_at (timestamp with time zone)
- redeemed_at (timestamp with time zone)
- status (text)

Schema for marketplace_listings:
- price (numeric)
- seller_id (integer)
- voucher_id (integer)
- id (integer)
- updated_at (timestamp without time zone)
- created_at (timestamp without time zone)
- status (character varying)