fix: projection dropping a cftime coord crashes batch reading#230
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fix: projection dropping a cftime coord crashes batch reading#230ghostiee-11 wants to merge 1 commit into
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iter_record_batches preloaded every dim's coord values and called schema.field(name) for cftime coords, but a projection (e.g. GROUP BY on a non-time dim) drops columns from the batch schema, so the lookup raised KeyError. Skip dims absent from the projected schema; they are never read in the batch loop, which iterates only the schema's fields.
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A projection that drops a cftime dimension coordinate (for example
GROUP BYon a non-time dim, which removestimefrom the scan) crashed withKeyError: 'Column time does not exist in schema'during batch reading.iter_record_batchespreloaded every dimension's coord values and calledschema.field(name)for cftime coords, but the projected batch schema no longer contains the dropped dim. datetime64 coords skip that branch, so only cftime datasets broke.The dropped dim is never read in the batch loop (it iterates only the schema's fields), so this skips preloading any dim absent from the projected schema.
Verified across all calendars (Gregorian/NoLeap mapped to timestamp, 360-day/Julian mapped to int64) and every projected dimension. The regression test in
test_df.pyfails without the fix (KeyError) and passes with it.