Spark DayTimeIntervalType support

[zhli1142015]

Hello,
I'm adding Spark function SubtractDates which result type is DayTimeIntervalType. Velox defines silimar internal type： IntervalDayTimeType.First I want to use it but I found although both types have a physical length of 8 bytes, but their semantics are different. Velox IntervalDayTimeType represents time interval in milliseconds. Spark DayTimeIntervalType represents time interval in microseconds.
Should I add a new custom type for Spark DayTimeIntervalType or map it to IntervalDayTimeType?
CC @mbasmanova @rui-mo @FelixYBW
Thanks.
https://spark.apache.org/docs/latest/sql-ref-datatypes.html

[rui-mo]

I wonder if it is feasible to use micro unit in IntervalDayTimeType and provide toMillis method just like TimestampType does.

[zhli1142015]

In Velox, the Timestamp type represents a time instant with nanosecond precision. It should be acceptable to adjust the precision to microseconds or milliseconds. However, applying this approach to the IntervalDayTimeType might reduce the data representation range for Presto. I'm unsure if this is a problem.

[mbasmanova]

@zhli1142015 It looks like in Spark DayTimeIntervalType has parameters. It is not a singleton type. If so, I think you need to define a new type.

[zhli1142015]

Thanks.