Re: Proposed patch: make SQL interval-literal syntax work per spec

Ron Mayer <rm_pg@cheapcomplexdevices.com> writes:
> Oh.  I wasn't proposing 8601-only.  Just the one-character
> shorthands like '1Y1M'::interval that postgresql interprets
> as "1 year one minute".   No standard specifies anything close
> to that; and any similar standards ask to interpret that M as
> months instead of minutes.

Hmmm.  I would say that the problem with that is not that it's
nonstandard but that it's ambiguous.  Our documentation about the
interval type says:
 interval values can be written with the following syntax:
   [@] quantity unit [quantity unit...] [direction]
 Where: quantity is a number (possibly signed); unit is microsecond, millisecond, second, minute, hour, day, week,
month,year, decade, century, millennium, or abbreviations or plurals of these units; direction can be ago or empty. The
atsign (@) is optional noise. The amounts of different units are implicitly added up with appropriate sign accounting.
agonegates all the fields.
 

There isn't anything there that would suggest to a user that 'm' is
well-defined as a unit, much less that it specifically means "minute"
rather than one of the other options.  What if we just tweak the code to
reject ambiguous abbreviations?

[ experiments a bit... ]  Another interesting point is that "mo",
which is a perfectly unique abbreviation, is rejected.  Seems like
the handling of abbreviations in this code could be improved.
        regards, tom lane