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.
New append_parquet() function to append a data frame
to an existing Parquet file.
New col_select argument for
read_parquet() to read a subset of columns from a Parquet
file.
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.
The class argument of parquet_options()
and the nanoparquet.class option now work again
(#104).
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.