Pailloncy Jean-Gerard <jg(at)rilk(dot)com> writes:
> I do not want for each column and each row to store the value and the
> unit.
> I do want to put the unit in the definition of the column and the check
> on the parser before any execution.
If you do that, you foreclose the ability to store mixed values in a
single column, in return for what? Saving a couple of bytes per value?
(I suppose that in a serious implementation we'd store the units as some
sort of reference, not as a string.) Compare the implementation of the
NUMERIC type: you *can* constrain a column to have a fixed precision,
but you do not *have* to.
regards, tom lane