[Spark] Reuse the column value skipping redundant access on row(i)

[bowenliang123]

🔍 Description

Issue References 🔗

Subtask of #5808

Describe Your Solution 🔧

• Avoid redundant access on row(i) in both the isNullAt(ordinal) and row.getAs[T](ordinal) by Reusing the column value

Types of changes 🔖

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Test Plan 🧪

Behavior Without This Pull Request ⚰️

Behavior With This Pull Request 🎉

Related Unit Tests

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Checklists

📝 Author Self Checklist

• My code follows the style guidelines of this project
• I have performed a self-review
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• This patch was not authored or co-authored using Generative Tooling

📝 Committer Pre-Merge Checklist

• Pull request title is okay.
• No license issues.
• Milestone correctly set?
• Test coverage is ok
• Assignees are selected.
• Minimum number of approvals
• No changes are requested

Be nice. Be informative.

[pan3793]

I think we can not make such an assumption, the implementation may be different, for example, the developer uses a custom value to represent NULL in its own CustomRow, especially for those non-JVM implementations

[pan3793]

meanwhile, the default implementation of Row is array-based, so indexed-access is cheap.

[bowenliang123]

1. No changes here, as the Spark's row.isNullAt checks the value equals to null of Java precisely
2. Thanks for hint. The default implementation of Row IS array-based.

[bowenliang123]

Based on the second point above in the discussion, access to the array-based columns inside the row should be cheap. this PR is not necessary. Closing this PR.