Robert Haas <robertmhaas@gmail.com> writes:
> The internal representation doesn't have to be (and certainly
> shouldn't be) numeric. But if you translate to numeric before
> returning the data to the user, then you have the freedom, in the
> future, to whack around the internal representation however you like,
> without breaking backward compatibility. Choosing float8 for the
> external representation is fine as long as we're sure we're not ever
> going to want more than 16 significant digits, but I see no particular
> value in baking in that assumption. But perhaps, as the saying goes,
> 16 digits ought to be enough for anyone.
There's no particular reason to think that Moore's Law is going to
result in an increase in the fractional precision of timing data.
It hasn't done so in the past, for sure.
regards, tom lane