Tom Lane wrote:
> somewhat SQL-compliant on interval input, a GUC that selected
> PG traditional, SQL-standard, or ISO 8601 interval output format seems
> like it could be a good idea.
Trying to do the SQL-standard output now, and have a question
of what to do in the SQL-standard mode when trying to output
an interval that as both a YEAR and a DAY component.
AFAICT the SQL standard doesn't let you have both, so the
"SQL-standard" output actually won't be.