alamb commented on issue #8156:
URL: https://github.com/apache/arrow-rs/issues/8156#issuecomment-3197185524
> For example, if you had a predicate of the form col > 34 it would only be
valid to push this down if the nan_counts are zero.
I think this is true if the system treats '-Nan` and `Nan` differently for
comparisons
It does appear to be the case that DataFusion treats `Nan`and `-Nan`
differently:
```sql
> create or replace table foo(x double) as values ('nan'), (34.0), (34.1),
('-nan');
0 row(s) fetched.
Elapsed 0.001 seconds.
> select x, x>34 from foo;
+------+-------------------+
| x | foo.x > Int64(34) |
+------+-------------------+
| NaN | true |
| 34.0 | false |
| 34.1 | true |
| NaN | false |
+------+-------------------+
4 row(s) fetched.
Elapsed 0.004 seconds.
```
However, Postgres does not 🤔
```sql
postgres=# create table foo (x real);
CREATE TABLE
postgres=# insert into foo values ('Nan'), (34.0), (34.1), ('-Nan');
INSERT 0 4
postgres=# select x, x>34 from foo;
x | ?column?
------+----------
NaN | t
34 | f
34.1 | t
NaN | t
(4 rows)
postgres=#
```
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