Columns names outputs are inconsistents and case sensitivie

[OutSquareCapital]

What happens?

Output of the code block:

PS C:\Users\tibo\python_codes\pql> uv run t.py
relation.columns: ['foo', 'Foo']
to_arrow_table: ['foo', 'Foo']
pl.from_arrow: ['foo', 'Foo']
relation.pl eager: ['foo', 'Foo_1']
relation.pl lazy: ['foo', 'Foo']
pandas result: ['foo', 'Foo_1']
arrow query result: ['foo', 'Foo']
PS C:\Users\tibo\python_codes\pql> 

pandas and polars dataframe don't give the same results as the rest.

To Reproduce

import duckdb
import polars as pl

rel = duckdb.from_query("select 1 as foo, 2 as Foo")

print("relation.columns:", rel.columns)
print("to_arrow_table:", rel.to_arrow_table().column_names)
print("pl.from_arrow:", pl.from_arrow(rel.to_arrow_table()).columns)
print("relation.pl eager:", rel.pl().columns)
print("relation.pl lazy:", rel.pl(lazy=True).collect().columns)
print("pandas result:", list(rel.df().columns))
print("arrow query result:", rel.to_arrow_reader().read_all().column_names)

OS:

Windows

DuckDB Package Version:

1.5.1

Python Version:

3.13.7

Full Name:

Stettler Thibaud

Affiliation:

University of Geneva

What is the latest build you tested with? If possible, we recommend testing with the latest nightly build.

1.5.2.dev40

Did you include all relevant data sets for reproducing the issue?

Yes

Did you include all code required to reproduce the issue?

• Yes, I have

Did you include all relevant configuration to reproduce the issue?

• Yes, I have