arrow (version 0.17.1)

write_parquet: Write Parquet file to disk

Description

Parquet is a columnar storage file format. This function enables you to write Parquet files from R.

Usage

write_parquet(
  x,
  sink,
  chunk_size = NULL,
  version = NULL,
  compression = NULL,
  compression_level = NULL,
  use_dictionary = NULL,
  write_statistics = NULL,
  data_page_size = NULL,
  properties = ParquetWriterProperties$create(x, version = version, compression =
    compression, compression_level = compression_level, use_dictionary = use_dictionary,
    write_statistics = write_statistics, data_page_size = data_page_size),
  use_deprecated_int96_timestamps = FALSE,
  coerce_timestamps = NULL,
  allow_truncated_timestamps = FALSE,
 
    arrow_properties = ParquetArrowWriterProperties$create(use_deprecated_int96_timestamps
    = use_deprecated_int96_timestamps, coerce_timestamps = coerce_timestamps,
    allow_truncated_timestamps = allow_truncated_timestamps)
)

Arguments

x

An arrow::Table, or an object convertible to it.

sink

an arrow::io::OutputStream or a string which is interpreted as a file path

chunk_size

chunk size in number of rows. If NULL, the total number of rows is used.

version

parquet version, "1.0" or "2.0". Default "1.0"

compression

compression algorithm. Default "snappy". See details.

compression_level

compression level. Meaning depends on compression algorithm

use_dictionary

Specify if we should use dictionary encoding. Default TRUE

write_statistics

Specify if we should write statistics. Default TRUE

data_page_size

Set a target threshold for the approximate encoded size of data pages within a column chunk (in bytes). Default 1 MiB.

properties

properties for parquet writer, derived from arguments version, compression, compression_level, use_dictionary, write_statistics and data_page_size. You should not specify any of these arguments if you also provide a properties argument, as they will be ignored.

use_deprecated_int96_timestamps

Write timestamps to INT96 Parquet format. Default FALSE.

coerce_timestamps

Cast timestamps a particular resolution. Can be NULL, "ms" or "us". Default NULL (no casting)

allow_truncated_timestamps

Allow loss of data when coercing timestamps to a particular resolution. E.g. if microsecond or nanosecond data is lost when coercing to "ms", do not raise an exception

arrow_properties

arrow specific writer properties, derived from arguments use_deprecated_int96_timestamps, coerce_timestamps and allow_truncated_timestamps You should not specify any of these arguments if you also provide a properties argument, as they will be ignored.

Value

the input x invisibly.

Details

The parameters compression, compression_level, use_dictionary and write_statistics support various patterns:

• The default NULL leaves the parameter unspecified, and the C++ library uses an appropriate default for each column (defaults listed above)

• A single, unnamed, value (e.g. a single string for compression) applies to all columns

• An unnamed vector, of the same size as the number of columns, to specify a value for each column, in positional order

• A named vector, to specify the value for the named columns, the default value for the setting is used when not supplied

The compression argument can be any of the following (case insensitive): "uncompressed", "snappy", "gzip", "brotli", "zstd", "lz4", "lzo" or "bz2". Only "uncompressed" is guaranteed to be available, but "snappy" and "gzip" are almost always included. See codec_is_available(). The default "snappy" is used if available, otherwise "uncompressed". To disable compression, set compression = "uncompressed". Note that "uncompressed" columns may still have dictionary encoding.

Examples

# NOT RUN {
tf1 <- tempfile(fileext = ".parquet")
write_parquet(data.frame(x = 1:5), tf1)

# using compression
if (codec_is_available("gzip")) {
  tf2 <- tempfile(fileext = ".gz.parquet")
  write_parquet(data.frame(x = 1:5), tf2, compression = "gzip", compression_level = 5)
}
# }