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Showing content from https://docs.databend.com/sql/sql-reference/file-format-options below:

Input & Output File Formats

Introduced or updated: v1.2.713

Databend accepts a variety of file formats both as a source and as a target for data loading or unloading. This page explains the supported file formats and their available options.

Syntax

To specify a file format in a statement, use the following syntax:


... FILE_FORMAT = ( TYPE = { CSV | TSV | NDJSON | PARQUET | ORC | AVRO } [ formatTypeOptions ] )


... FILE_FORMAT = ( FORMAT_NAME = '<your-custom-format>' )
formatTypeOptions

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:

RECORD_DELIMITER

Separates records in an input file.

Available Values:

Default: \n

FIELD_DELIMITER

Separates fields in a record.

Available Values:

Default: , (comma)

QUOTE (Load Only)

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.

Available Values: ', ", or `(backtick)

Default: "

ESCAPE

Escapes a quote in a quoted string.

Available Values: '\\' or ''

Default: ''

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

Default: 0

NAN_DISPLAY (Load Only)

Specifies how "NaN" (Not-a-Number) values are displayed in query results.

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

Default: 'NaN'

NULL_DISPLAY (Load Only)

Specifies how NULL values are displayed in query results.

Default: '\N'

ERROR_ON_COLUMN_COUNT_MISMATCH (Load Only)

ERROR_ON_COLUMN_COUNT_MISMATCH is a boolean option that, when set to true, specifies that an error should be raised if the number of columns in the data file doesn't match the number of columns in the destination table. Setting it to true helps ensure data integrity and consistency during the loading process.

Default: true

EMPTY_FIELD_AS (Load Only)

Specifies the value that should be used when encountering empty fields, including both ,, and ,"",, in the CSV data being loaded into the table.

Available Values Description null (Default) Interprets empty fields as NULL values. Applicable to nullable columns only. string Interprets empty fields as empty strings (''). Applicable to String columns only. field_default Uses the column's default value for empty fields.

Specifies whether to include a header row in the CSV file when exporting data with the COPY INTO <location> command. Defaults to false.

BINARY_FORMAT

Controls the binary encoding format during both data export and import operations, with available values HEX (default) and BASE64.

COMPRESSION

Specifies the compression algorithm.

Available Values Description NONE (Default) Indicates that the files are not compressed. 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 TSV Options

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

note

  1. In Databend, the main difference between TSV and CSV is NOT using a tab instead of a comma as a field delemiter (which can be changed by options), but using escaping instead of quoting for delimter collision
  2. We recommend CSV over TSV as a storage format since it has a formal standard.
  3. TSV can be used to load files generated by
    1. Clickhouse TSV file format.
    2. MySQL mysqldump command with option --tab without --fields-enclosed-by or --fields-optinally-enclosed-by, if the later two is specified, use CSV instead.
    3. Snowflake CSV without ESCAPE_UNENCLOSED_FIELD. if ESCAPE_UNENCLOSED_FIELD is specified, use CSV instead.
RECORD_DELIMITER

Separates records in an input file.

Available Values:

Default: \n

FIELD_DELIMITER

Separates fields in a record.

Available Values:

Default: \t (TAB)

COMPRESSION

Same as the COMPRESSION option for CSV.

NDJSON Options NULL_FIELD_AS (Load Only)

Specifies how to handle null values during data loading. Refer to the options in the table below for possible configurations.

Available Values Description NULL (Default) Interprets null values as NULL for nullable fields. An error will be generated for non-nullable fields. FIELD_DEFAULT Uses the default value of the field for null values. MISSING_FIELD_AS (Load Only)

Determines the behavior when encountering missing fields during data loading. Refer to the options in the table below for possible configurations.

Available Values Description ERROR (Default) Generates an error if a missing field is encountered. NULL Interprets missing fields as NULL values. An error will be generated for non-nullable fields. FIELD_DEFAULT Uses the default value of the field for missing fields. COMPRESSION

Same as the COMPRESSION option for CSV.

PARQUET Options MISSING_FIELD_AS (Load Only)

Determines the behavior when encountering missing fields during data loading. Refer to the options in the table below for possible configurations.

Available Values Description ERROR (Default) Generates an error if a missing field is encountered. FIELD_DEFAULT Uses the default value of the field for missing fields. COMPRESSION (Unload Only)

Specifies the compression algorithm, which is used for compressing internal blocks of the file rather than the entire file, so the output remains in Parquet format.

Available Values Description ZSTD (default) Zstandard v0.8 (and higher) is supported. SNAPPY Snappy is a popular and fast compression algorithm often used with Parquet. ORC Options MISSING_FIELD_AS (Load Only)

Determines the behavior when encountering missing fields during data loading. Refer to the options in the table below for possible configurations.

Available Values Description ERROR (Default) Generates an error if a missing field is encountered. FIELD_DEFAULT Uses the default value of the field for missing fields. AVRO Options MISSING_FIELD_AS (Load Only)

Determines the behavior when encountering missing fields during data loading. Refer to the options in the table below for possible configurations.

Available Values Description ERROR (Default) Generates an error if a missing field is encountered. FIELD_DEFAULT Uses the default value of the field for missing fields.

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