Karl Dunkle Werner created ARROW-7035:
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Summary: [R] Default arguments are unclear in write_parquet docs
Key: ARROW-7035
URL: https://issues.apache.org/jira/browse/ARROW-7035
Project: Apache Arrow
Issue Type: Improvement
Components: R
Affects Versions: 0.15.0
Environment: Ubuntu with libparquet-dev 0.15.0-1, R 3.6.1, and arrow
0.15.0.
Reporter: Karl Dunkle Werner
Fix For: 0.15.1
Thank you so much for adding support for reading and writing parquet files in
R! I have a few questions about the user interface and optional arguments, but
I want to highlight how great it is to have this useful filetype to pass data
back and forth.
The defaults for the optional arguments in {{arrow::write_parquet}} aren't
always clear. Here were my questions after reading the help docs from
{{write_parquet}}:
* What's the default {{version}}? Should a user prefer "2.0" for new projects?
* What are acceptable values for {{compression}}? (Answer: {{uncompressed}},
{{snappy}}, {{gzip}}, {{brotli}}, {{zstd}}, or {{lz4}}.)
* What's the default for {{use_dictionary}}? Seems to be {{TRUE}}, at least
some of the time.
* What's the default for {{write_statistics}}? Should a user prefer {{TRUE}}?
* Can I assume {{allow_truncated_timestamps}} is {{FALSE}} by default?
As someone who works in both R and Python, I was a little surprised when
pyarrow uses snappy compression by default, but R's default is uncompressed. My
preference would be having the same default arguments, but that might be a
fringe use-case.
While I was digging into this, I was surprised that {{ParquetReaderProperties}}
is exported and documented, but {{ParquetWriterProperties}} isn't. Is that
intentional?
Thanks!
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