hanyuzheng7 commented on PR #25759:
URL: https://github.com/apache/flink/pull/25759#issuecomment-2539107679
@snuyanzin
The reason we not support `millisecond`/`nanosecond` is that floor and ceil
not support these two perfectly. You can see here
``` /**
* Keep the algorithm consistent with Calcite
DateTimeUtils.julianDateFloor, but here we take
* time zone into account.
*/
public static long timestampCeil(TimeUnitRange range, long ts, TimeZone
tz) {
// assume that we are at UTC timezone, just for algorithm performance
long offset = tz.getOffset(ts);
long utcTs = ts + offset;
switch (range) {
case NANOSECOND:
return ceil(utcTs, 1L) - offset;
case MILLISECOND:
return ceil(utcTs, MILLIS_PER_MINUTE) - offset;
case SECOND:
return ceil(utcTs, MILLIS_PER_SECOND) - offset;
case MINUTE:
return ceil(utcTs, MILLIS_PER_MINUTE) - offset;
case HOUR:
return ceil(utcTs, MILLIS_PER_HOUR) - offset;
case DAY:
return ceil(utcTs, MILLIS_PER_DAY) - offset;
case MILLENNIUM:
case CENTURY:
case DECADE:
case MONTH:
case YEAR:
case QUARTER:
case WEEK:
int days = (int) (utcTs / MILLIS_PER_DAY + EPOCH_JULIAN);
return julianDateFloor(range, days, false) * MILLIS_PER_DAY
- offset;
default:
// for MINUTE and SECONDS etc...,
// it is more effective to use arithmetic Method
throw new AssertionError(range);
}
}
```
for DAY and HOUR now base on
```
/** The number of milliseconds in a second. */
private static final long MILLIS_PER_SECOND = 1000L;
/** The number of milliseconds in a minute. */
private static final long MILLIS_PER_MINUTE = 60000L;
/** The number of milliseconds in an hour. */
private static final long MILLIS_PER_HOUR = 3600000L; // = 60 * 60 * 1000
/**
* The number of milliseconds in a day.
*
* <p>This is the modulo 'mask' used when converting TIMESTAMP values to
DATE and TIME values.
*/
public static final long MILLIS_PER_DAY = 86400000L; // = 24 * 60 * 60 *
1000
```
We can use 1L to stand for MILLIS_PER_MILLISECOND, but how can we stand
for NANOSECOND, is smaller than MILLISECOND?
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