Input & Output File Formats

Databend accepts a variety of file formats both as a source and as a target for data loading or unloading. For example, you can load data into Databend from a file with the COPY INTO table command or the Streaming Load API. You can also unload data from Databend into a file with the COPY INTO location command command. To do so, you need to tell Databend what the file looks like using the following syntax:

FILE_FORMAT = ( TYPE = { CSV | TSV | NDJSON | PARQUET | XML } [ formatTypeOptions ] )

Type: Specifies the file format. Must be one of the ones listed above that Databend supports.

备注

Databend currently supports XML as a source ONLY. Unloading data into an XML file is not supported yet.

If FILE_FORMAT is not specified, use FILE_FORMAT = (TYPE = PARQUET) by default.

formatTypeOptions: Includes one or more options to describe other format details about the file. The options vary depending on the file format. See the sections below to find out the available options for each supported file format.

formatTypeOptions ::=
  RECORD_DELIMITER = '<character>'
  FIELD_DELIMITER = '<character>'
  SKIP_HEADER = <integer>
  QUOTE = '<character>'
  ESCAPE = '<character>'
  NAN_DISPLAY = '<string>'
  ROW_TAG = '<string>'
  COMPRESSION = AUTO | GZIP | BZ2 | BROTLI | ZSTD | DEFLATE | RAW_DEFLATE | XZ | NONE

CSV Options

Databend accepts CVS files that are compliant with RFC 4180 and is subject to the following conditions:

• A string must be quoted if it contains the character of a QUOTE, ESCAPE, RECORD_DELIMITER, or FIELD_DELIMITER.
• No character will be escaped in a quoted string except QUOTE.
• No space should be left between a FIELD_DELIMITER and a QUOTE.
• A string will be quoted in CSV if it comes from a serialized Array or Struct field.
• If you develop a program and generate the CSV files from it, Databend recommends using the CSV library from the programing language.
• Databend does not recognize the files unloaded from MySQL as the CSV format unless the following conditions are satisfied:
  • ESCAPED BY is empty.
  • ENCLOSED BY is not empty.
    备注

    Files will be recognized as the TSV format if the conditions above are not satisfied. For more information about the clauses ESCAPED BY and ENCLOSED BY, refer to https://dev.mysql.com/doc/refman/8.0/en/load-data.html.

RECORD_DELIMITER

Separates records in an input file.

Available Values:

• \r\n
• An arbitrary character, such as a and |.
• A character with the escape char: \b, \f, \r, \n, \t, \0, \xHH

Default: \n

FIELD_DELIMITER

Separates fields in a record.

Available Values:

• \r\n
• An arbitrary character, such as a and |.
• A character with the escape char: \b, \f, \r, \n, \t, \0, \xHH

Default: , (comma)

QUOTE

Quotes strings in a CSV file. For data loading, the quote is not necessary unless a string contains the character of a QUOTE, ESCAPE, RECORD_DELIMITER, or FIELD_DELIMITER.

备注

Used for data loading ONLY: This option is not available when you unload data from Databend.

Available Values: \' or \".

Default: \"

ESCAPE

Escapes a quote in a quoted string.

Available Values: \' or \" or \\.

Default: \"

SKIP_HEADER

Specifies how many lines to be skipped from the beginning of the file.

备注

Used for data loading ONLY: This option is not available when you unload data from Databend.

Default: 0

NAN_DISPLAY

Available Values: Must be literal 'nan' or 'null' (case-insensitive)

Default: 'NaN'

COMPRESSION

Specifies the compression algorithm.

Default: NONE

Available Values:

Values	Notes
AUTO	Auto detect compression via file extensions
GZIP
BZ2
BROTLI	Must be specified if loading/unloading Brotli-compressed files.
ZSTD	Zstandard v0.8 (and higher) is supported.
DEFLATE	Deflate-compressed files (with zlib header, RFC1950).
RAW_DEFLATE	Deflate-compressed files (without any header, RFC1951).
XZ
NONE	Indicates that the files have not been compressed.

TSV Options

Databend is subject to the following conditions when dealing with a TSV file:

• These characters in a TSV file will be escaped: \b, \f, \r, \n, \t, \0, \\, \', RECORD_DELIMITER, FIELD_DELIMITER.
• Neither quoting nor enclosing is currently supported.
• A string will be quoted in CSV if it comes from a serialized Array or Struct field.
• Null is serialized as \N.

RECORD_DELIMITER

Separates records in an input file.

Available Values:

• \r\n
• An arbitrary character, such as a and |.
• A character with the escape char: \b, \f, \r, \n, \t, \0, \xHH

Default: \n

FIELD_DELIMITER

Separates fields in a record.

Available Values:

• \r\n
• An arbitrary character, such as a and |.
• A character with the escape char: \b, \f, \r, \n, \t, \0, \xHH

Default: \t (TAB)

COMPRESSION

Same as the COMPRESSION option for CSV.

NDJSON Options

COMPRESSION

Same as the COMPRESSION option for CSV.

PARQUET Options

No available options.

XML Options

COMPRESSION

Same as the COMPRESSION option for CSV.

ROW_TAG

Used to select XML elements to be decoded as a record.

Default: 'row'