CREATE TYPE header_pair AS (
    name TEXT,
    value BYTEA
);

CREATE TABLE idempotency (
    user_id UUID NOT NULL REFERENCES users(id),
    nonce TEXT NOT NULL,
    response_code SMALLINT NOT NULL,
    response_headers header_pair[] NOT NULL,
    response_body BYTEA NOT NULL,
    created_at timestamptz NOT NULL,
    PRIMARY KEY(user_id, nonce)
);