CREATE TABLE IF NOT EXISTS orders (
    id          BIGSERIAL PRIMARY KEY,
    order_id    VARCHAR(64) NOT NULL,
    customer_id VARCHAR(64) NOT NULL,
    amount      NUMERIC(18, 2) NOT NULL,
    natural_key VARCHAR(255) NOT NULL UNIQUE,
    created_at  TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX IF NOT EXISTS idx_orders_customer_created
    ON orders (customer_id, created_at);