suremarc commented on issue #8838:
URL:
https://github.com/apache/arrow-datafusion/issues/8838#issuecomment-1920144404
Just to make sure we're all on the same page, I think the first case (single
order by expression) already works due to monotonicity, and I think `CAST` is
considered monotonic. In the original post I mentioned that the following query
does not require a sort, due to having only one sorting column:
```sql
EXPLAIN
SELECT
CAST(c_customer_sk AS BIGINT) AS c_customer_sk_big
FROM delta_encoding_required_column
ORDER BY c_customer_sk_big DESC;
```
The second case (multiple order by expressions) is the troublesome one,
because I think monotonicity alone is not sufficient (that's where
one-to-one-ness becomes relevant).
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