haohuaijin opened a new issue, #26108:
URL: https://github.com/apache/datafusion/issues/26108
### Is your feature request related to a problem or challenge?
Queries over ordered timestamp data can require an unnecessary sort after
applying `to_timestamp_micros` or `to_unixtime`, even when these conversions
preserve the input ordering.
For example, given a table ordered by `micros ASC NULLS LAST`:
```sql
SELECT to_unixtime(
date_bin(
INTERVAL '1 second',
to_timestamp_micros(micros),
TIMESTAMP '1970-01-01'
)
) AS bucket
FROM ordered_timestamps
ORDER BY bucket ASC NULLS LAST;
```
The conversion chain preserves ordering, but the resulting plan currently
includes a `SortExec`.
### Describe the solution you'd like
Allow DataFusion to propagate ordering through:
- `to_timestamp_micros` with a single integer argument.
- `to_unixtime` with a single integer, date, or timestamp argument.
Preserve the input sort direction and NULL placement so redundant sorts can
be removed.
Precision reduction can produce equal output values, so sorting by
additional keys must remain when their ordering cannot be established.
### Describe alternatives you've considered
Keep the existing explicit sort. This produces correct results but performs
unnecessary work when the converted values are already ordered.
### Additional context
_No response_
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