fix(parquet): preserve dictionary index types - #1098
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zeroshade merged 1 commit intoAug 7, 2026
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fallintoplace
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fallintoplace
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zeroshade
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Aug 6, 2026
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Rationale for this change
Parquet dictionary encoding uses int32 indexes, but stored Arrow schema metadata can specify a different dictionary index type. The schema restoration path currently hardcodes int32 and changes the dictionary type and index buffer width on read.
What changes are included in this PR?
Restore the stored index type and safely cast the reader indexes before rebuilding each dictionary array. Preserve dictionary values and the ordered flag.
Are these changes tested?
go test ./parquet/pqarrow -run TestArrowDictionaryTypePreservesIndexType -count=1Are there any user-facing changes?
No API changes. This corrects the reported behavior while preserving the existing ownership and compatibility contracts.