[jira] [Created] (ARROW-7035) [R] Default arguments are unclear in write_parquet docs

["Karl Dunkle Werner (Jira)" <ji...@apache.org>]

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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