Re: Patch for SQL-Standard Interval output and decoupling DateStyle from IntervalStyle

Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com> writes:
> Brendan Jurd wrote:
>> The changes to the documentation all look good. I did notice one
>> final typo that I think was introduced in the latest version.
>> doc/src/sgml/datatype.sgml:2270 has "Nonstandardrd" instead of
>> "Nonstandard".

> Just checked in a fix to that one; and updated my website at
> http://0ape.com/postgres_interval_patches/
> and pushed it to my (hopefully fixed now) git server.

> If this'll be the final update to this patch should I be
> posting it to the mailing list too for the archives?

Since it's only one line different from your previous, probably no need.

I've started reviewing this patch for commit, and I find myself a bit
disturbed by its compatibility properties. The SQL_STANDARD output
style is simply ambiguous: what is meant by
-1 1:00:00
? What you get from that will depend on the intervalstyle setting at
the recipient. Either of the traditional Postgres styles are
non-ambiguous and will be interpreted correctly regardless of receiver's
intervalstyle --- in particular, Postgres mode always puts an explicit
sign on the time part if the days or months part was negative. What
this means is that SQL_STANDARD mode is unsafe for dumping data, and
*pg_dump had better force Postgres mode*. We can certainly do that with
a couple more lines added to the patch, but it's a bit troublesome that
we are boxed into using a nonstandard dump-data format until forever.

I don't immediately see any way around that, though. Anyone have a
bright idea?

regards, tom lane