Major Description
See Table 9.31. Date/Time Functions (https://www.postgresql.org/docs/12/functions-datetime.html)
| justify_days(interval) | interval | Adjust interval so 30-day time periods are represented as months | justify_days(interval '35 days') | 1 mon 5 days |
| justify_hours(interval) | interval | Adjust interval so 24-hour time periods are represented as days | justify_hours(interval '27 hours') | 1 day 03:00:00 |
| justify_interval(interval) | interval | Adjust interval using justify_days and justify_hours, with additional sign adjustments | justify_interval(interval '1 mon -1 hour') | 29 days 23:00:00 |