apache / apache/arrow

Mixing RLE_DICTIONARY and other column encodings in pyarrow parquet

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#43,442 4 comments 0 reactions 0 assignees View on GitHub
Component: Parquet Component: Python Type: bug
Dominant language
C++
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Description

### Describe the bug, including details regarding any error messages, version, and platform.

The ValueError at https://github.com/apache/arrow/blob/aaeff72dd9cb4658913fde3d176416be9a93ebe0/python/pyarrow/_parquet.pyx#L1360-L1367 will raise anytime any column is custom encoded with a dictionary method. This makes it impossible to mix a dictionary encoded column with something like `DELTA_BINARY_PACKED`. I understand this is to prevent duplication of `use_dictionary`. Would it be okay to move this ValueError to the calling function instead? Does anything at the C++ level prevent this? https://github.com/apache/arrow/blob/aaeff72dd9cb4658913fde3d176416be9a93ebe0/python/pyarrow/_parquet.pyx#L1971-L1972

### Component(s)

Parquet, Python

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