from_df fails with std::bad_cast on a reversed DataFrame mixing string and float columns

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Evaluación

Dificultad
3/5
Tiempo estimado
1-2 días
Aptitud para principiantes
66/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
pandas, python
Área
backend, databases

Línea de trabajo

Start by reading the Python DataFrame registration path used by DuckDBPyConnection.from_df and the replacement scan, then look for tests covering reversed pandas views and mixed column types. Reproduce with the issue's two-column example and compare it with the copied frame. Done when both entry points handle the negative-stride view and a regression test verifies the result.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

What happens?

DuckDBPyConnection.from_df (and a replacement scan of the same frame) fails on a DataFrame that is a negative-stride view, such as df.iloc[::-1], when it mixes a string (object or str) column with a float column. On 2.0.0 the error is std::bad_cast; on 1.3.2 and 1.5.6 it is Unable to cast Python instance of type <class 'int'> to C++ type '?'.

A copy of the same view (df.iloc[::-1].copy()) works, and so does a reversed frame with a single column, or with only string columns.

To Reproduce
import duckdb
import pandas as pd

df = pd.DataFrame({"a": ["x", "y"], "b": [1.0, 2.0]})
duckdb.connect().from_df(df.iloc[::-1]).fetchall()
# duckdb.Error: std::bad_cast

duckdb.connect().from_df(df.iloc[::-1].copy()).fetchall()
# [('y', 2.0), ('x', 1.0)]
DuckDB pandas result
2.0.0 3.1.1 std::bad_cast
2.0.0 2.3.3 std::bad_cast
1.5.6 3.1.1 Unable to cast Python instance of type <class 'int'> to C++ type '?'
1.3.2 2.3.3 Unable to cast Python instance of type <class 'int'> to C++ type '?'
OS:

Linux x86_64 (Pop!_OS, kernel 7.2)

DuckDB Package Version:

2.0.0

Python Version:

3.13.2

Full Name:

Jonas Hörsch

Affiliation:

Open Energy Transition

What is the latest build you tested with?

2.0.0 from PyPI (latest release)

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

Not applicable: the reproduction creates its own data.

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
Lenguaje dominante
Python
Estrellas
203
Forks
124
Merge medio
13 h 36 min
PR fusionados (30 d)
61

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