[quinnj]

Calling collect(Tables.partitions(dataset)) fails with a MethodError for length(::Parquet.DatasetPartitions). This iterator walks and filters files lazily, but inherits Julia's default HasLength contract without implementing length.

Declare its size as unknown, as specified by the Julia iteration interface. Keep the existing file traversal and filtering behavior. Add public collection tests through both Dataset and read_parquet, covering all, one, and no selected data files, exclusion of metadata files, and decoded row values. The separate table partition iterator retains its existing length contract.

Validation: the unchanged reader passes six manual-iteration controls and fails six collection controls on both actual Julia 1.3.1 and 1.13.1. All 30 focused checks pass after this fix. The complete suites pass with four threads and bounds checking: 4,092 checks on Julia 1.3.1 and 4,078 on Julia 1.13.1. An independent agent privately reviewed the complete source/test diff and found no blocker. git diff --check passes.

Hosted validation at 8d621a9b1304822a638a403d629dbda6184e4f42: all nine Julia 1.3/current/nightly jobs on Linux, macOS, and Windows and both coverage checks pass. Each uploader log confirms acceptance for this repository and commit; all nine reports are processed at 86.62%.

Merged validation at 426c4a7ba8c3c51d0c424c0eb3cec8f00ad913aa: all nine merge jobs pass, with all nine correct-repository uploads accepted and processed at 86.62%. The merged tree matches the tested tree.

Co-authored by Codex

AI disclosure: This work was prepared with assistance from OpenAI Codex.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.62%. Comparing base (7824e2e) to head (8d621a9).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #202   +/-   ##
=======================================
  Coverage   86.61%   86.62%           
=======================================
  Files          10       10           
  Lines        1599     1600    +1     
=======================================
+ Hits         1385     1386    +1     
  Misses        214      214           

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