> idempotency<p>Even with the ability to detect that something is a retry, there are more wrinkles, like a query that involves NOW() which would be correct to run <i>now</i>-now [0], but would not accomplish the desired result if run 15 seconds later. Or uses of RAND(), unless there's some control over the seed.<p>[0] <a href="https://www.youtube.com/watch?v=nRGCZh5A8T4&t=1m17s" rel="nofollow">https://www.youtube.com/watch?v=nRGCZh5A8T4&t=1m17s</a>