cjrh opened a new issue, #46629: URL: https://github.com/apache/arrow/issues/46629
### Describe the bug, including details regarding any error messages, version, and platform. This issue was first posed as a question in #30302. I repeat the text here for convenience. # Overview I have a directory of parquet files. For a specific categorical column, some parquet files use int8 and some use int16. In pyarrow 19.0.1, reading the directory as a dataset succeeds. But with pyarrow 20, it fails with the below error when loading data from the dataset directory # Reader code (python) Either ```python import pandas as pd df = pd.read_parquet( path, engine="pyarrow", ) ``` or ``` import pyarrow.dataset as dataset dataset = dataset.dataset(path, format="parquet") table = dataset.to_table() df = table.to_pandas() ``` # Traceback ... File "/app/venv/lib/python3.12/site-packages/pyarrow/parquet/core.py", line 1475, in read table = self._dataset.to_table( ^^^^^^^^^^^^^^^^^^^^^^^ File "pyarrow/_dataset.pyx", line 589, in pyarrow._dataset.Dataset.to_table File "pyarrow/_dataset.pyx", line 3941, in pyarrow._dataset.Scanner.to_table File "pyarrow/error.pxi", line 155, in pyarrow.lib.pyarrow_internal_check_status File "pyarrow/error.pxi", line 92, in pyarrow.lib.check_status pyarrow.lib.ArrowInvalid: Integer value 731 not in range: -128 to 127 # Parquet Metadata This shows the dictionary info of the parquet files in the directory: >>> import pyarrow.dataset as dataset >>> ds = dataset(path) >>> for path in ds.files: ... sch = pq.read_schema(path) ... print(path, sch.field('ExpStartDate').type) ... dataframes.parq/00eac90ef2f504223a74498405e060a48.parquet dictionary<values=string, indices=int8, ordered=0> dataframes.parq/0641c30f725cd448bafc335d36cd01f6b.parquet dictionary<values=string, indices=int16, ordered=0> dataframes.parq/0cb2799478dd54c738efe76fdc1875326.parquet dictionary<values=string, indices=int8, ordered=0> dataframes.parq/0cff477be69be4ee093d98728d4f84452.parquet dictionary<values=string, indices=int16, ordered=0> dataframes.parq/0d103de6323904e93aecf24589c12a370.parquet dictionary<values=string, indices=int8, ordered=0> Is my issue related to the change in #30302 ? Is there a way to restore the previous behaviour of upcasting to int32 on read? Or what is the preferred workaround? It is going to be quite tedious to have to force all my writes to use int32, and especially for migrating huge volumes of historical data. For now we remain on pyarrow 19.0.1, but at some point we would like to upgrade. ### Component(s) C++, Parquet, Python -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@arrow.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org