[BugFix] fix samples rows calculation error when sampling to collect table statistics

[stephen-shelby]

Why I'm doing:

What I'm doing:

we should use sampled tablets to calculate sample rows. currenty we use all tablets to calculate it.

Fixes #issue

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 3.4
  • 3.3
  • 3.2
  • 3.1
  • 3.0

[starrocks-cr]

The most risky bug in this code is:
The variable sampleRows is declared twice, which can cause confusion and potential logical errors. The first declaration is not necessary if it is redefined later.

You can modify the code like this:

public void classifyPartitions(Table table, List<Long> partitions) {

    long totalRows = high.getTotalRows() + mediumHigh.getTotalRows() + mediumLow.getTotalRows()
            + low.getTotalRows();
    // Remove the initial declaration of sampleRows
    // long sampleRows = high.getSampleRows() + mediumHigh.getSampleRows() + mediumLow.getSampleRows()
    //        + low.getSampleRows();

    List<TabletStats> highSampleTablets = high.sample();
    List<TabletStats> mediumHighSampleTablets = mediumHigh.sample();
    List<TabletStats> mediumLowSampleTablets = mediumLow.sample();
    List<TabletStats> lowSampleTablets = low.sample();

    long sampleRows = Math.min(sampleRowsLimit, highSampleTablets.stream()
            .mapToLong(e -> getReadRowCount(e.getRowCount(), highRatio))
            .sum());
    sampleRows += Math.min(sampleRowsLimit, mediumHighSampleTablets.stream()
            .mapToLong(e -> getReadRowCount(e.getRowCount(), mediumHighRatio))
            .sum());
    sampleRows += Math.min(sampleRowsLimit, mediumLowSampleTablets.stream()
            .mapToLong(e -> getReadRowCount(e.getRowCount(), mediumLowRatio))
            .sum());
    sampleRows += Math.min(sampleRowsLimit, lowSampleTablets.stream()
            .mapToLong(e -> getReadRowCount(e.getRowCount(), lowRatio))
            .sum());
    sampleRows = Math.max(1, sampleRows);

    long totalTablets = high.getTotalTablets() + mediumHigh.getTotalTablets() + mediumLow.getTotalTablets() +
            low.getTotalTablets();
    long sampleTablets = highSampleTablets.size() + mediumHighSampleTablets.size()
            + mediumLowSampleTablets.size() + lowSampleTablets.size();
}

This change removes the unnecessary initial definition of sampleRows before it's properly defined further down in the code, thus reducing potential confusion or errors.

[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

[Java-Extensions Incremental Coverage Report]

✅ pass : 0 / 0 (0%)

[github-actions]

[FE Incremental Coverage Report]

✅ pass : 14 / 14 (100.00%)

file detail

	path	covered_line	new_line	coverage	not_covered_line_detail
🔵	com/starrocks/statistic/base/PartitionSampler.java	14	14	100.00%	[]

[github-actions]

[BE Incremental Coverage Report]

✅ pass : 0 / 0 (0%)