API changes:
parquet_schema() is now called read_parquet_schema(). The new
parquet_schema() function falls back to read_parquet_schema() if
it is called with a single string argument, with a warning.
parquet_info() is now called read_parquet_info(). parquet_info(
still works for now, with a warning.
parquet_metadata() is now called read_parquet_metadata().
parquet_metadata() still works, with a warning.
parquet_column_types() is now deprecated, and issues a warning. Use
read_parquet_schema() or the new infer_parquet_schema() function
instead.
Other improvements:
The new parquet_schema() function creates a Parquet schema from
scratch. You can use this schema as the new schema argument of
write_parquet(), to specify how the columns of a data frame should
be mapped to Parquet types.
write_parquet() can now write multiple row groups. By default it puts
at most 10 million rows into a single row group. You can choose the
row groups manually with the row_groups argument.
write_parquet() now writes minimum and maximum values per row group
for most types. See ?parquet_options() for turning this off. It also
writes out the number of non-missing values.
Newly supported type conversions in write_parquet() via the
schema argument:
integer to INT64,integer to INT96,double to INT96,double to FLOAT,character to BYTE_ARRAY,character to FIXED_LEN_BYTE_ARRAY,character to ENUM,factor to ENUM.integer to DECIMAL, INT32,integer to DECIMAL, INT64,double to DECIMAL, INT32,double to DECIMAL, INT64,integer to INT(8, *), INT(16, *), INT(32, signed),double to INT(*, *),character to UUID,double to FLOAT16,list of raw vectors to BYTE_ARRAY,list of raw vectors to FIXED_LEN_BYTE_ARRAY.write_parquet() can now write version 2 data pages. The default is
still version 1, but it might change in the future.
write_parquet(file = ":raw:") now works correctly for larger data
frames (#77).
New compression_level option to select the compression level
manually. See ?parquet_options for details. (#91).
read_parquet() can now read from an R connection (#71).
read_parquet() now reads DECIMAL values correctly from INT32
and INT64 columns if their scale is not zero.
read_parquet() now reads JSON columns as character vectors, as
documented.
read_parquet() now reads the FLOAT16 logical type as a real (double)
vector.
write_parquet() crash (#73).read_parquet() type mapping changes:
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.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).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.