fix(python): Support for ADBC drivers instantiated with dbc in DataFrame.write_database

[henryharbeck]

Closes #26103
Supersedes #25889 (thanks @0x0Aro)

write_database used to assume that an instantiated ADBC connections had a corresponding Python package for the driver installed. With the recently released dbc cli, this is no longer required.

This is not specifically tested in CI, as the dbc cli is not installed there. The changes have been verified locally.

---

Repro

Install dbc and add postgresql (in the example here)

uv tool install dbc
dbc install postgresql

Script

from adbc_driver_manager import dbapi
import polars as pl

def main():
    df = pl.DataFrame({"a": [1, 2, 3], "b": ["x", "y", "z"]})

    uri = "postgresql://postgres:postgres@localhost:5432"
    with dbapi.connect("postgresql", uri=uri) as conn:
        df.write_database("my_table", conn, if_table_exists="replace")
        # Prove the data was written
        out = pl.read_database("SELECT * FROM my_table", conn)
        print(out)

if __name__ == "__main__":
    main()

Before: raises even though an instantiated connection is passed to write_database

ModuleNotFoundError: ADBC 'adbc_driver_postgresql' driver not detected.
If ADBC supports this database, please run: pip install adbc-driver-postgresql

After:

shape: (3, 2)
┌─────┬─────┐
│ a   ┆ b   │
│ --- ┆ --- │
│ i64 ┆ str │
╞═════╪═════╡
│ 1   ┆ x   │
│ 2   ┆ y   │
│ 3   ┆ z   │
└─────┴─────┘

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.66%. Comparing base (9d60226) to head (a3fe4f4).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
py-polars/src/polars/dataframe/frame.py	71.42%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #26157      +/-   ##
==========================================
+ Coverage   81.00%   81.66%   +0.66%     
==========================================
  Files        1805     1805              
  Lines      248021   248024       +3     
  Branches     3132     3131       -1     
==========================================
+ Hits       200902   202551    +1649     
+ Misses      46313    44668    -1645     
+ Partials      806      805       -1     

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[ritchie46]

@alexander-beedie can you review?

[alexander-beedie]

@alexander-beedie can you review?

@ritchie46 No problem, will get on it tomorrow - this renewed ADBC driver push from the Columnar folks is likely to become relevant with things I'm doing at work too 🤔

[alexander-beedie]

Finally started reviewing (apologies for the delay); so far, so good. Will run a few local experiments (at home tonight) and merge tomorrow if all is well 👍

[henryharbeck]

Let me know how you get on @alexander-beedie
Happy to talk through the change or provide examples for any other databases/drivers

And sorry for the ping - just keen to get this in the next release!

[henryharbeck]

@alexander-beedie - friendly ping. Your review would be greatly appreciated.
Is a small fix so shouldn't be too much effort to review

[0x0Aro]

@henryharbeck Hi. Sorry for the late response, I've been watching this change closely for the recent couple weeks now. Since it is yet to be merged, would it be possible for I to take it back? It means a lot as a first time open source contributor. Appreciate your time in this change.