[SPARK-54750][SQL] Fix ROUND returning NULL for Decimal values with l…

[qindongliang]

What changes were proposed in this pull request?

Fixed a bug in RoundBase where ROUND function incorrectly returns NULL for certain Decimal values. The issue was caused by using the input decimal's runtime precision instead of the target type's precision when calling toPrecision().

For example, ROUND(PERCENTILE_APPROX(2150 / 1000.0, 0.95), 3) incorrectly returned NULL instead of 2.15.

Why are the changes needed?

The fix changes decimal.toPrecision(decimal.precision, s, mode) to decimal.toPrecision(p, s, mode) in both nullSafeEval and doGenCode methods, where p is the target DecimalType's precision.

Does this PR introduce any user-facing change?

Yes, this fixes a bug where ROUND could return NULL for valid decimal inputs.

How was this patch tested?

Added regression test in ApproximatePercentileQuerySuite.

Was this patch authored or co-authored using generative AI tooling?

No.

[qindongliang]

Jira: https://issues.apache.org/jira/browse/SPARK-54750

[qindongliang]

Hi @yaooqinn @gengliangwang
The CI failure in "Base image build" is expected for external contributors due to GitHub's security restrictions on GHCR package writes from forked PRs.
Could you please help trigger the official CI when convenient? Thanks!

[yaooqinn]

LGTM

[yaooqinn]

@qindongliang, can you make the GA green? I speculate it is due to your GitHub settings.

[qindongliang]

@qindongliang, can you make the GA green? I speculate it is due to your GitHub settings.

Hi @yaooqinn,

Thank you for triggering the CI. I investigated the failure and found the root cause:

The build itself succeeded (all layers are cached from Apache's registry), but the push
to ghcr.io/qindongliang/apache-spark-ci-image-docs:... failed with permission_denied: write_package.

This happens because:

1. The workflow uses ${{ github.repository_owner }} to generate the image URL,
   which becomes ghcr.io/qindongliang/... in my fork
2. GitHub doesn't allow Actions to automatically create new packages in the Container Registry
3. I've already set "Read and write permissions" for workflows in my repo settings,
   but it still doesn't work for creating new packages

My questions:

1. Is there a recommended way to configure fork repos to allow pushing to ghcr.io?
   Should I manually create placeholder packages first?
2. Or could you run the CI directly from the apache/spark side where the packages
   already exist?

Any guidance would be appreciated. Thank you!

[qlong]

LGTM

[yaooqinn]

I'm not familiar with this area either, maybe you can check https://github.com/qindongliang?tab=packages for what is missing

[qindongliang]

Thanks @yaooqinn! @qlong

I found the issue - I needed to grant my home repo write access to the packages in GitHub Container Registry settings.

The image push is now successful. CI is currently building and should turn green soon if everything goes smoothly. ✅

Reference: https://github.com/orgs/community/discussions/32184

[yaooqinn]

Merged to master and '4.1.1', '4.0.2', '3.5.8'