Arik Funke created ARROW-6416:
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Summary: [Python] Confusing API & documentation regarding
chunksizes
Key: ARROW-6416
URL: https://issues.apache.org/jira/browse/ARROW-6416
Project: Apache Arrow
Issue Type: Bug
Reporter: Arik Funke
The python API and documentation regarding chunksizes is confusing in my
opinion:
Example:
[https://arrow.apache.org/docs/python/generated/pyarrow.RecordBatchFileWriter.html#pyarrow.RecordBatchFileWriter.write_table]
{color:#0000ff}def{color}
{color:#795e26}write_table{color}{color:#000000}({color}{color:#001080}self{color}{color:#000000},
Table {color}{color:#001080}table{color}{color:#000000},
{color}{color:#001080}chunksize{color}{color:#000000}={color}{color:#0000ff}None{color}{color:#000000}):{color}
{color:#a31515}"""{color}
{color:#a31515} Write RecordBatch to stream{color}
{color:#a31515} Parameters{color}
{color:#a31515} ----------{color}
{color:#a31515} batch : RecordBatch{color}
This suggests, the file will be written with a fixed chunk size when in fact
the {{chunksize}} parameter is an upper bound on the size of the chunks to be
written.
In my opinion this parameter should be renamed {{max_chunksize}} to avoid
confusion and reflect its true purpose.
This would also improve naming consistency in the code base, since in the C++
implementation, this parameter is already named {{max_chunksize}} in
{{cpp/source/arrow/ipc/writer.cc}}:
{color:#000000}Status
{color}{color:#267f99}RecordBatchWriter{color}{color:#000000}::{color}{color:#795e26}WriteTable{color}{color:#000000}({color}{color:#0000ff}const{color}{color:#000000}
Table{color}{color:#000000}&{color}{color:#001080}
table{color}{color:#000000}, {color}{color:#0000ff}int64_t{color}
{color:#001080}max_chunksize{color}{color:#000000}) {{color}
Similarly, the parameter should be renamed in {{pyarrow.Table.to_batches(self,
chunksize=None)}}.
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