nanoparquet v0.3.0

• read_parquet() type mapping changes:

  • The STRING logical type and the UTF8 converted type are still read
    as a character vector, but BYTE_ARRAY types without a converted or
    logical types are not any more, and are read as a list of raw vectors.
    Missing values are indicated as NULL values.
  • The DECIMAL converted type is read as a REALSXP now, even if its
    type is FIXED_LEN_BYTE_ARRAY. (Not just if it is BYTE_ARRAY).
  • The UUID logical type is now read as a character vector, formatted as
    00112233-4455-6677-8899-aabbccddeeff.
  • BYTE_ARRAY and FIXED_LEN_BYTE_ARRAY types without logical or
    converted types; or with unsupported ones: FLOAT16, INTERVAL; are
    now read into a list of raw vectors. Missing values are denoted by
    NULL.

• write_parquet() now automatically uses dictionary encoding for columns
  that have many repeated values. Only the first 10k rows are used to
  decide if dictionary will be used or not. Similarly, logical columns are
  written in RLE encoding if they contain runs of repeated values.
  NA values are ignored when selecting the encoding (#18).

• write_parquet() can now write a data frame to a memory buffer, returned
  as a raw vector, if the special ":raw:" filename is used (#31).

• read_parquet() can now read Parquet files with V2 data pages (#37).

• Both read_parquet() and write_parquet() now support GZIP and ZSTD
  compressed Parquet files.

• read_parquet() now supports the RLE encoding for BOOLEAN columns
  and also supports the DELTA_BINARY_PACKED, DELTA_LENGTH_BYTE_ARRAY,
  DELTA_BYTE_ARRAY and BYTE_STREAM_SPLIT encodings.

• The parquet_columns() function is now called parquet_column_types()
  and it can now map the column types of a data frame to Parquet types.

• parquet_info(), parquet_metadata() and parquet_column_types() now
  work if the created_by metadata field is unset.

• New parquet_options() function that you can use to set nanoparquet
  options for a single read_parquet() or write_parquet() call.