Ability to have optional extra dependencies

[matt035343]

• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the FAQ and general documentation and believe that my question is not already covered.

Feature Request

With pandas 2.0 also comes optional dependencies. However, I only sometimes need some of the extras, depending on the selected extras in my own project, to avoid bloating of the installation. For example, in my Poetry project I always need pandas, but only when my database extra is installed, the pandas SQL extra dependencies (postgresql, mysql, sql-other) should be installed.
I currently have not found a way to do this that the installed extra dependencies of a dependency can depend on the extra chosen for my own project.

I believe there are multiple ways of going about this, I have two suggestions below.

Being able to label dependency specifications and use those in the extra specification

[tool.poetry]
name = "packagename"
version = "0.0.0"
description = "..."
authors = ["..."]
maintainers = ['...']
license = 'Apache 2.0'
readme = "README.md"
repository = 'https://github.com/...'

[tool.poetry.dependencies]
python = ">=3.9, <3.12"
pandas = { version = "^2.0.0"}
pandas = { version = "^2.0.0", extras = ["performance", "postgresql", "mysql", "sql-other"], label="pandas-databases", optional=true }


[tool.poetry.extras]
databases = [
    'SQLAlchemy',
    'pyodbc',
    'pandas-databases'
]

Use a notation similar to pip in the extra specification, potentially with declaration of optional extras

[tool.poetry]
name = "packagename"
version = "0.0.0"
description = "..."
authors = ["..."]
maintainers = ['...']
license = 'Apache 2.0'
readme = "README.md"
repository = 'https://github.com/...'

[tool.poetry.dependencies]
python = ">=3.9, <3.12"
pandas = { version = "^2.0.0", optional_extras=["performance", "postgresql", "mysql", "sql-other"]}


[tool.poetry.extras]
databases = [
    'SQLAlchemy',
    'pyodbc',
    'pandas[performance,postgresql,mysql,sql-other]'
]

[dimbleby]

duplicate #834, #3913, #5733, #6053, #7738, ...

[george-zubrienko]

duplicate #834, #3913, #5733, #6053, #7738, ...

Alright, to be fair this is not a small repo, so assessing whether this is a duplicate or not is not easy from outside the contributor circle. I've read all those linked issues and the conclusion is, this is not possible atm? Or how should we understand a variable list of issue hyperlinks?

[github-actions]

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