Minor Description
While converting dates with negative years to strings, Spark skips era sub-field by default. That's can confuse users since years from BC era are mirrored to current era. For example:
spark-sql> select make_date(-44, 3, 15); 0045-03-15
Even negative years are out of supported range by the DATE type, it would be nice to indicate the era for such dates.
PostgreSQL outputs the era for such inputs:
# select make_date(-44, 3, 15); make_date --------------- 0044-03-15 BC (1 row)