Behaviour when multiple samples with same timestamp is submitted

[arkocal]

Only one sample is saved for a component when multiple have the same timestamp. I think this is problematic, because of the following:

1. We have a resolution of ms, which can be insufficient for some applications.
2. There is no feedback that only one is saved, possibly creating difficult to spot bugs in user applications.

We should at least properly document this behavior. It could also make sense to return an error or warning when this occurs. It would be expensive to make a check against the data storage, but we can at least check whether there are samples with the same timestamp within a request.

[wagmarcel]

I am not sure whether this is a true problem. When you get two measurements from a sensor at the same time, then I'd think we have two metrics. If we get two different values of the same metrics with the same timestamp, then the sensor is broken ;-)
True, it might be of interest to give warnings. Implementation could be e.g. backend gives instead of 201 (create) a (e.g. 209 Overwritten) and frontend forwards it. But then, I am not sure whether I'd give this a high priority. For every write to the backend, you'd have to do a read-request first. I'd prefer to leave this sanity testing to the sender. So, yes, documenting and leave it would be the best option.