SNOW-966003: Fix Arrow return value for zero-row queries

[sfc-gh-aling]

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1. What GitHub issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Fixes SNOW-966003, dup PR: SNOW-966003: Fix Arrow return value for zero-row queries #1801 (comment)

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[sfc-gh-mkeller]

Other than the overloading this is good to go by me.

🚢 🚢

[sfc-gh-mkeller]

🚢 🚢

[thomasaarholt]

The type signature came from me writing this in vscode with the pyright type checker.

Looks like mypy and pyright have slightly different behaviour. pyright allows my usage, while mypy does not. Here is a version that satisfies both . I believe the return type of None when Literal[False] is provided, is correct.

from typing import Literal, overload, reveal_type, NewType

Table = NewType("Table", object)


class Foo:
    @overload
    def fetch_arrow_all(self, force_return_table: Literal[False]) -> None:
        ...

    @overload
    def fetch_arrow_all(self, force_return_table: Literal[True]) -> Table:
        ...

    def fetch_arrow_all(self, force_return_table: bool = False) -> Table | None:
        return Table(1) if force_return_table else None


fetch_true = Foo().fetch_arrow_all(True)
fetch_false = Foo().fetch_arrow_all(False)
reveal_type(fetch_true)  # Table
reveal_type(fetch_false)  # None

[sfc-gh-aling]

thanks @sfc-gh-mkeller @thomasaarholt , I have applied the change.
I do agree with Mark that when it's force_return_table is False, it should be the old Table | None as for non-zero row result, pyarrow.Table is returned.

[thomasaarholt]

Apologies, I was blinded by what the correct return type. You're absolutely right.

[sfc-gh-aling]

no worries @thomasaarholt , you are all good!
I merged this PR and the change will be carried in our 2024 Jan release.
thanks for your contribution!