amoeba opened a new issue, #15043: URL: https://github.com/apache/arrow/issues/15043
### Describe the bug, including details regarding any error messages, version, and platform. The docstring for `decompressed_size` in `pyarrow.decompress` and the underlying `Codec.decompress` states: > decompressed_size : int, default None > If not specified, will be computed if the codec is able to determine the uncompressed buffer size. However, you can see from the implementation that the behavior isn't possibly and that the argument is effectively required because we always raise when it's `None`: https://github.com/apache/arrow/blob/4e9158d373df105f01ba9d6052cfb9ab7ecdcbeb/python/pyarrow/io.pxi#L2091-L2124 For example, ```python import pyarrow as pa pa.decompress(pa.compress(bytes('mydata','utf-8'))) ``` Raises: > ValueError: Must pass decompressed_size for <pyarrow.Codec name=lz4 compression_level=1> codec I think the [original intent](https://github.com/apache/arrow/pull/1345) was to support detecting or estimating the size of the output buffer for codecs that support it (like Snappy) but, the last time [this was brought up](https://issues.apache.org/jira/browse/ARROW-3877), it was marked as low priority and remains unimplemented. Should the argument be made required and the bit about "If not specified" be removed? ### Component(s) 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
