fix(SelectQuery): process the last partial chunk in runChunks()

[roxblnfk]

🔍 What was changed

SelectQuery::runChunks() no longer skips the last partial chunk.

The loop guard was $offset + $limit <= $count, which required a full remaining chunk and stopped as soon as fewer than $limit rows were left. The trailing partial page ($count % $limit rows) was silently dropped — no error, no warning. The guard is changed to $offset < $count, so the final iteration issues LIMIT N OFFSET k and naturally returns the remaining < $limit rows.

Note

The same guard also broke the limit > count case entirely: a table with fewer rows than the chunk size processed zero rows. This is fixed by the same change and covered by a dedicated test.

🤔 Why?

Silent data loss in any batch/export/migration built on runChunks(). Full coverage previously happened only when $count was an exact multiple of $limit.

Example — 2500 rows, runChunks(1000, …):

offset=0     0+1000 <= 2500  ✓  → rows 0…999
offset=1000  1000+1000<=2500 ✓  → rows 1000…1999
offset=2000  2000+1000<=2500 ✗  → STOP
                                  rows 2000…2499  NEVER processed

📝 Checklist

• Closes [Bug]: SelectQuery::runChunks() silently skips the last partial chunk (data loss) #254

• How was this tested:

  • Tested manually
  • Unit tests added

  Added regression and edge-case tests to StatementTest (common across all drivers):

  • testChunksProcessLastPartialChunk — trailing partial page is visited (count % limit != 0)
  • testChunksWithLimitGreaterThanCount — chunk size larger than the row count still yields every row
  • testChunksPassOffsetAndCountToCallback — $offset/$count callback arguments
  • testChunksOnEmptyResultNeverInvokesCallback — empty result set never invokes the callback

📃 Documentation

Not needed — behavioral bugfix, public API unchanged.

[Copilot]

Pull request overview

Fixes a data-loss bug in SelectQuery::runChunks() where the final partial chunk (and the limit > count case) could be skipped, and adds regression tests to ensure all rows are processed across chunk boundaries.

Changes:

• Update SelectQuery::runChunks() loop guard to process the trailing partial chunk ($offset < $count).
• Add functional regression tests covering partial tail chunks, limit > count, empty results, and callback offset/count arguments.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/Query/SelectQuery.php	Adjusts chunk iteration condition so the final partial page is not skipped.
tests/Database/Functional/Driver/Common/Driver/StatementTest.php	Adds new test cases validating chunk traversal behavior and callback arguments.

Comments suppressed due to low confidence (1)

src/Query/SelectQuery.php:312

• runChunks() can enter an infinite loop when $limit <= 0 (because $offset never increases meaningfully, and the loop guard only checks $offset < $count). Since runChunks() accepts any int, it should validate that the chunk size is a positive integer and fail fast with an exception to avoid hanging processes.

        while ($offset < $count) {
            $result = $callback(
                $select->offset($offset)->getIterator(),
                $offset,
                $count,

---

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.68%. Comparing base (c4d40ce) to head (b4bf8a9).
⚠️ Report is 1 commits behind head on 2.x.

Additional details and impacted files

@@            Coverage Diff            @@
##                2.x     #255   +/-   ##
=========================================
  Coverage     95.68%   95.68%           
  Complexity     2038     2038           
=========================================
  Files           137      137           
  Lines          5775     5775           
=========================================
  Hits           5526     5526           
  Misses          249      249           

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