Fix the issue that comparison function could not handle decimal arguments with different scales

[zanmato1984]

apache#47378)

Rationale for this change

In order to support special form (apache#47374), the kernels have to respect the selection vector. Currently none of the kernels does. And it's almost impossible for us to make all existing kernels to respect the selection vector at once (and we probably never will). Thus we need an incremental way to add selection-vector-aware kernels on demand, meanwhile accommodate legacy (selection-vector-non-aware) kernels to be executed "selection-vector-aware"-ly in a general manner - the idea is to first "gather" selected rows from the batch into a new batch, evaluate the expression on the new batch, then "scatter" the result rows into the positions where they belong in the original batch.

This makes the take and scatter functions dependencies of the exec facilities, which is in compute core (libarrow). And take is already in compute core. Now we need to move scatter.

I'm implementing the selective execution of kernels in apache#47377, including invoking take and scatter as explained above. And I have to write tests of that in exec_test.cc which is deliberately declared to be NOT depending on libarrow_compute.

What changes are included in this PR?

Move scatter compute function into compute core.

Are these changes tested?

Yes. Manually tested.

Are there any user-facing changes?

None.

• GitHub Issue: [C++][Compute] Move scatter function into compute core apache/arrow#47375

Authored-by: Rossi Sun zanmato1984@gmail.com
Signed-off-by: Rossi Sun zanmato1984@gmail.comThanks for opening a pull request!

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Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

This PR includes breaking changes to public APIs. (If there are any breaking changes to public APIs, please explain which changes are breaking. If not, you can remove this.)

This PR contains a "Critical Fix". (If the changes fix either (a) a security vulnerability, (b) a bug that caused incorrect or invalid data to be produced, or (c) a bug that causes a crash (even when the API contract is upheld), please provide explanation. If not, you can remove this.)

[zanmato1984]

ok

[github-actions]

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