Does Datafusion support manually specifying the timestamp and time precision?

[caicancai]

Here is a quote from the postgres documentation: https://www.postgresql.org/docs/16/datatype-datetime.html

time, timestamp, and interval accept an optional precision value p which specifies the number of fractional digits retained in the seconds field. By default, there is no explicit bound on precision. The allowed range of p is from 0 to 6.

[findepi]

On SQL frontend layer, only timestamp is currently supported and is synonymous to timestamp(9):

datafusion/datafusion/sql/src/planner.rs

Lines 457 to 469 in 18b2aaa

	SQLDataType::Timestamp(None, tz_info) => {
	let tz = if matches!(tz_info, TimezoneInfo::Tz)
	|| matches!(tz_info, TimezoneInfo::WithTimeZone)
	{
	// Timestamp With Time Zone
	// INPUT : [SQLDataType] TimestampTz + [RuntimeConfig] Time Zone
	// OUTPUT: [ArrowDataType] Timestamp<TimeUnit, Some(Time Zone)>
	self.context_provider.options().execution.time_zone.clone()
	} else {
	// Timestamp Without Time zone
	None
	};
	Ok(DataType::Timestamp(TimeUnit::Nanosecond, tz.map(Into::into)))

Other timestamp types are accessible via arrow_cast

datafusion/datafusion/sqllogictest/test_files/timestamps.slt

Lines 36 to 46 in a2e5330

	statement ok
	create table ts_data_nanos as select arrow_cast(ts, 'Timestamp(Nanosecond, None)') as ts, value from ts_data;
	statement ok
	create table ts_data_micros as select arrow_cast(ts / 1000, 'Timestamp(Microsecond, None)') as ts, value from ts_data;
	statement ok
	create table ts_data_millis as select arrow_cast(ts / 1000000, 'Timestamp(Millisecond, None)') as ts, value from ts_data;
	statement ok
	create table ts_data_secs as select arrow_cast(ts / 1000000000, 'Timestamp(Second, None)') as ts, value from ts_data;

I think we should add SQL-level timestamp(p) support as well -- #13231

[caicancai]

Thanks for your answer