Architecture Intermediate

Idempotency — Safe Operation Retries¶

IdempotencyAPIReliability 3 min read

Implementing idempotent APIs. Idempotency keys and database techniques.

What Is Idempotency?¶

Multiple executions = same result. GET, PUT, DELETE are naturally idempotent. POST is not.

Idempotency Key¶

app.post('/api/payments', async (req, res) => {
    const key = req.headers['idempotency-key'];
    if (!key) return res.status(400).json({ error: 'Missing key' });

    const existing = await redis.get(\`idem:\${key}\`);
    if (existing) return res.json(JSON.parse(existing));

    const result = await processPayment(req.body);
    await redis.setex(\`idem:\${key}\`, 86400, JSON.stringify(result));
    res.status(201).json(result);
});

DB Idempotency¶

INSERT INTO orders (external_id, customer_id, total)
VALUES ('ord-123', 'cust-456', 1000)
ON CONFLICT (external_id) DO NOTHING RETURNING *;

Summary¶

Implement idempotency keys for POST/PATCH. Always expect repeated requests.

Need Help with Implementation?¶

Our team has experience designing and implementing modern architectures. We’re happy to help.

Free Consultation