Add sqlalchemy as optional dependency for Postgres provider

[mohit7705]

Closes #59905

What does this PR do?

Adds SQLAlchemy as an optional dependency for the Postgres provider.

Why is this needed?

This aligns the Postgres provider with task isolation requirements, where SQLAlchemy should not be a mandatory dependency unless explicitly required.

[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide (https://github.com/apache/airflow/blob/main/contributing-docs/README.rst)
Here are some useful points:

• Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
• In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example DAG that shows how users should use it.
• Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
• Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
• Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
• Be sure to read the Airflow Coding style.
• Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
  Apache Airflow is a community-driven project and together we are making it better 🚀.
  In case of doubts contact the developers at:
  Mailing List: dev@airflow.apache.org
  Slack: https://s.apache.org/airflow-slack

[potiuk]

It's quite a bit more than that - see at other PRs in sibling issues (conditional handling of imports and sqlalchemy version difference)

[mohit7705]

Thanks for the guidance!
I’ve aligned the Postgres provider changes with the conditional import pattern and optional SQLAlchemy handling used in sibling provider PRs.
Please let me know if you’d like me to adjust anything further.

[mohit7705]

Thanks for the review!
I’ve fixed the indentation issue and updated the branch with latest main.
Could you please take another look when you have time?

[jscheffl]

Can you please - without just shooting code as a PR - run basic tests locally via prek? Basic indent is not fitting again and again. All would be fixed with local checks before pushing.

[potiuk]

Yes. It adds a lot of overhead if you dont follow basic contributing guides - this makes us loose more time to review and react to it than if we did it ourselves, and you do not seem to be self-reliant on fixing even those issues that are fixable automatically by prek

Not very helpful

[Srabasti]

Line 92 should be referencing "sqlalchemy>=1.4.49" instead of "sqlalchemy>=1.4".
Happy New Year!

[Srabasti]

Thanks for including the changes for Line 92 @mohit7705! However, looks like static checks are failing as below.

As Jens and Jarek advised above, have you reproduced locally by running prek run --all-files in your branch?
Prek will fix any formatting errors, and then you can push the commit from your branch.

To run prek as part of git workflow, use prek install to set up git hooks.

[potiuk]

Indeed, fixing the other static checks needed

[potiuk]

Type-hinting will be needed of the URL (making it Any).

[potiuk]

It's the type hinting - not setting "Any"

URL: Any baically.

[mohit7705]

can you verify once again @potiuk

[jscheffl]

You can take a look here where corrections were made: https://github.com/apache/airflow/pull/60094/changes#diff-d2d44a709cc687a2a6c390995289cba7689683c39519b81bab4bdd50f00c9bafR28

One other option (which I'd prefer actually) is also making it with lazy imports like in: https://github.com/apache/airflow/pull/60110/changes#diff-60967e11945bf5adce44c15269d657d1ff09ed8916f91e82ba1cf1beddf1e9a7R183

[mohit7705]

Thanks for the clarification, this makes sense 👍

I see the earlier approach and the alternative with lazy imports you linked. I’m happy to align with the preferred direction — please let me know if you’d like me to update this PR to use lazy imports instead, or if the current approach is acceptable as-is.

[potiuk]

Actusally deleting it is wrong. The conditional logic should still be used.

[mohit7705]

Thanks for the clarification — that makes sense 👍
I’ll restore the conditional logic and adjust the SQLAlchemy import to be MyPy-safe while keeping it optional.
I’ll push an updated commit shortly.

[potiuk]

This will likely fail with MyPy issues.