Interval Literal output inconsistent date_type

[waitingkuo]

Describe the bug
A clear and concise description of what the bug is.

the output of INTERVAL XXX is inconsistent

To Reproduce
Steps to reproduce the behavior:

while we only have year or month, it outputs IntervalYearMonth

❯ select interval '1 year';
+------------------------------------------------+
| IntervalYearMonth("12")                        |
+------------------------------------------------+
| 1 years 0 mons 0 days 0 hours 0 mins 0.00 secs |
+------------------------------------------------+
1 row in set. Query took 0.001 seconds.
❯ select interval '1 year 1 month';
+------------------------------------------------+
| IntervalYearMonth("13")                        |
+------------------------------------------------+
| 1 years 1 mons 0 days 0 hours 0 mins 0.00 secs |
+------------------------------------------------+

while we have (year or month) and any other unit, it outputs IntervalMonthDayNano

+--------------------------------------------------------+
| IntervalMonthDayNano("950737950189618795196236955648") |
+--------------------------------------------------------+
| 0 years 12 mons 1 days 0 hours 0 mins 0.00 secs        |
+--------------------------------------------------------+
1 row in set. Query took 0.001 seconds.
❯ select interval '1 year 1 second';
+--------------------------------------------------------+
| IntervalMonthDayNano("950737950171172051123527404032") |
+--------------------------------------------------------+
| 0 years 12 mons 0 days 0 hours 0 mins 1.00 secs        |
+--------------------------------------------------------+
1 row in set. Query took 0.001 seconds.

Otherwise, it outputs IntervalDaytime

❯ select interval '1 second';
+------------------------------------------------+
| IntervalDayTime("1000")                        |
+------------------------------------------------+
| 0 years 0 mons 0 days 0 hours 0 mins 1.00 secs |
+------------------------------------------------+
1 row in set. Query took 0.001 seconds.
❯ select interval '1 day 1 second';
+------------------------------------------------+
| IntervalDayTime("4294968296")                  |
+------------------------------------------------+
| 0 years 0 mons 1 days 0 hours 0 mins 1.00 secs |
+------------------------------------------------+
1 row in set. Query took 0.001 seconds.

Expected behavior
A clear and concise description of what you expected to happen.

they should be consistent, as our current Timestamp is in nanosecond, i suggest using IntervalMonthDayNano. We could consider add functions to output specific data type(i.e. to_interval_monthdaynano(), to_interval_daytime(), interval_yearmonth() . But i think they might need different arithmetics

Additional context
Add any other context about the problem here.

[waitingkuo]

just found that it's designed in purpose. let me close this and fire another ticket for discussing