fix(python): Harden alchemy session for old sqlalchemy versions

[brunobbaraujo]

Harden alchemy session for old sqlalchemy versions.

A similar fix was made before for the sqlalchemy engine to avoid import errors on old sqlalchemy packages (<2.0).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.72%. Comparing base (663fe4c) to head (20d888a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #17366      +/-   ##
==========================================
- Coverage   80.72%   80.72%   -0.01%     
==========================================
  Files        1475     1475              
  Lines      193383   193387       +4     
  Branches     2760     2761       +1     
==========================================
- Hits       156113   156102      -11     
- Misses      36760    36775      +15     
  Partials      510      510              

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[brunobbaraujo]

As stated in the sqlalchemy documentation, the async_sessiomaker is a new feature for SQLAlchemy >= 2.0. After making the change proposed changes in this pull request, I was able to use pl.read_database(query, session.connection()) in my code with SQLAlchemy 1.4.52

[brunobbaraujo]

Here's a sequence of steps on how to reproduce the error:

Install the version of SQLAlchemy

pip install 'sqlalchemy<2'

Then

import os

import polars as pl
from dotenv import load_dotenv
from sqlalchemy import create_engine, select
from sqlalchemy.orm.session import Session, sessionmaker

load_dotenv()

db_host = os.getenv("DB_HOST")
db_port = os.getenv("DB_PORT")
db_name = os.getenv("DB_NAME")
db_user = os.getenv("DB_USER")
db_password = os.getenv("DB_PASSWORD")

engine = create_engine(
    f"postgresql+psycopg2://{db_user}:{db_password}@{db_host}:{db_port}/{db_name}"
)
with sessionmaker(engine).begin() as session:
      print(pl.read_database(select(1), session.connection()))

[ritchie46]

Thanks!