Write Parquet file to disk

Source: R/parquet.R

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

write_parquet(
  x,
  sink,
  chunk_size = NULL,
  version = NULL,
  compression = default_parquet_compression(),
  compression_level = NULL,
  use_dictionary = NULL,
  write_statistics = NULL,
  data_page_size = NULL,
  use_deprecated_int96_timestamps = FALSE,
  coerce_timestamps = NULL,
  allow_truncated_timestamps = FALSE
)

Arguments

x

data.frame, RecordBatch, or Table
sink

A string file path, URI, or OutputStream, or path in a file system (SubTreeFileSystem)
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". Numeric values are coerced to character.
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.
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

Value

the input x invisibly.

Details

Due to features of the format, Parquet files cannot be appended to. If you want to use the Parquet format but also want the ability to extend your dataset, you can write to additional Parquet files and then treat the whole directory of files as a Dataset you can query. See vignette("dataset", package = "arrow") for examples of this.

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

# \donttest{
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)
}
# }