Re: [I] [Python] Categorical boolean column saved as regular boolean in parquet [arrow]

["jingyi-zhao-01 (via GitHub)" <gi...@apache.org>]

jingyi-zhao-01 commented on issue #29017:
URL: https://github.com/apache/arrow/issues/29017#issuecomment-4959929784

   I reproduced this on current Arrow main / local PyArrow dev build:
   
   - pyarrow `26.0.0.dev3+gb03b4c539`
   - pandas `3.0.3`
   
   Observed round-trip behavior:
   
   ```text
   bool_category
     written arrow type:    dictionary<values=bool, indices=int8, ordered=0>
     read arrow type:       bool
     read pandas dtype:     bool
     pandas category kept:  False
   
   int_category
     written arrow type:    dictionary<values=int64, indices=int8, ordered=0>
     read arrow type:       int64
     read pandas dtype:     int64
     pandas category kept:  False
   
   string_category
     written arrow type:    dictionary<values=large_string, indices=int8, ordered=0>
     read arrow type:       dictionary<values=string, indices=int8, ordered=0>
     read pandas dtype:     category
     pandas category kept:  True
   ```
   
   This still appears consistent with the earlier analysis in this thread: `IsDictionaryReadSupported` currently only allows binary/string dictionary reads in `cpp/src/parquet/arrow/schema.cc`.
   
   Related note: the broader tracker for non-`BYTE_ARRAY` direct dictionary decoding, https://github.com/apache/arrow/issues/22534 / ARROW-6140, is now closed as stale rather than fixed.
   
   Minimal ask: should this issue stay open as the Python-facing symptom, or should the non-`BYTE_ARRAY` dictionary decoding tracker be reopened / replaced with a fresh C++ Parquet issue? Happy to help keep a small reproducer or regression test attached once maintainers confirm the preferred direction.
   


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