Fly-a-Kite opened a new issue, #22554:
URL: https://github.com/apache/datafusion/issues/22554
### Describe the bug
`SELECT DISTINCT v FROM t0 ORDER BY v ASC NULLS FIRST LIMIT 1` should return
the first row of the same ordered `DISTINCT` query without `LIMIT`. On
DataFusion `53.0.0`, the full ordered query puts `NULL` first, but adding
`LIMIT 1` returns the first non-null value for string, integer, and float
columns.
### To Reproduce
## Environment
```text
OS: Ubuntu 24.04.1 x86_64
Python: 3.12.3
datafusion: 53.0.0
pyarrow: 24.0.0
```
## Reproduce
```python
import pyarrow as pa
from datafusion import SessionContext
ctx = SessionContext()
batch = pa.RecordBatch.from_pylist(
[{"v": None}, {"v": ""}, {"v": "a"}],
schema=pa.schema([pa.field("v", pa.string(), nullable=True)]),
)
ctx.register_record_batches("t0", [[batch]])
full_sql = "SELECT DISTINCT v FROM t0 ORDER BY v ASC NULLS FIRST"
top1_sql = full_sql + " LIMIT 1"
full = ctx.sql(full_sql).collect()[0].to_pydict()["v"]
top1 = ctx.sql(top1_sql).collect()[0].to_pydict()["v"]
print("full:", full)
print("top1:", top1)
assert top1 == full[:1]
```
## Output
```text
full: [None, '', 'a']
top1: [None]
```
### Expected behavior
```text
full: [None, '', 'a']
top1: ['']
```
### Additional context
_No response_
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