Is it appropriate to return HTTP 503 in response to a database deadlock?

Question

Is it appropriate for a server to return 503 ("Service Unavailable") when the requested operation resulted in a database deadlock?

Here is my reasoning:

• Initially I tried avoiding database deadlocks, but I ran across https://stackoverflow.com/a/112256/14731
• Next, I tried repeating the request on the server-side, but I ran across Java Servlets: How to repeat an HTTP request?. Technically speaking I can buffer the request entity but scalability will suffer and clients are more likely to see 503 Service Unavailable anyway.

Seeing as:

• It's easier to ask clients to repeat the operation.
• They need to be able to handle 503 Service Unavailable anyway.
• Database deadlocks are rather rare.

I'm leaning towards this solution. What do you think?

UPDATE: I think returning 503 ("Service Unavailable") is still acceptable if you wish it, but I no longer think it is technically required. See https://stackoverflow.com/a/17960047/14731.

Answer 1

I think it's fine so long as the entire transaction is rolled back or if the request is idempotent.