- The precision of the returned timestamp is same as the precision set for the current data base in use
- If the input data is not formatted as a timestamp, the returned value is null.
- If `1d` is used as `time_unit` to truncate the timestamp, `ignore_timezone` option can be set to indicate if the returned result is affected by client timezone or not.
For example, if client timezone is set to UTC+0800, TIMETRUNCATE('2020-01-01 23:00:00', 1d, 0) will return '2020-01-01 08:00:00'.
Otherwise, TIMETRUNCATE('2020-01-01 23:00:00', 1d, 1) will return '2020-01-01 00:00:00'.
If `ignore_timezone` option is omitted, the default value is set to 1.