Improve rows iterator performance

[shssoichiro]

Using chunks_exact avoids the inclusion of bounds checks in the generated assembly in certain cases, leading to better optimization.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.48%. Comparing base (cc73787) to head (fabcd6d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #45      +/-   ##
==========================================
+ Coverage   97.45%   97.48%   +0.03%     
==========================================
  Files           3        3              
  Lines         314      318       +4     
==========================================
+ Hits          306      310       +4     
  Misses          8        8              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.