Answer by Brendan · Feb 17 at 10:20 PM
Since each key is distinct, writing to all of them is not a single atomic operation. So technically, it's possible for one to be updated and not another from a single call. In practice, that would be exceedingly rare (and would result in an error response, allowing you to know to check the data or re-submit it). The much more common issue would be a call to set data which has an error (missing or invalid parameters, exceeding limits, etc.), in which case none of the data would be updated, as the call would be rejected.