I also have a use case that would benefit from nanosecond resolution in Python's datetime objects, that is, representing and querying the results of clock_gettime() in a program trace.

On modern Linuxes with a vDSO, clock_gettime() does not require a system call and completes within a few nanoseconds. So Python's datetime objects do not have sufficient resolution to distinguish between adjacent calls to clock_gettime().

This means that, like Mark Dickinson above, I have to choose between using datetime for queries (which would be convenient) and accepting that nearby events in the trace may be indistinguishable, or implementing my own datetime-like data structure.