Preparing to unload data

This topic provides an overview of supported data file formats for unloading data.

Supported file formats

The following file formats are supported:

Structured/Semi-structured

Type

Notes

Structured

Delimited (CSV, TSV, etc.)

Any valid singlebyte delimiter is supported; default is comma (i.e. CSV).

Semi-structured

JSON, Parquet

File format options specify the type of data contained in a file, as well as other related characteristics about the format of the data. The file format options you can specify are different depending on the type of data you are unloading to. Snowflake provides a full set of file format option defaults.

Semi-structured data

When unloading to JSON files, Snowflake outputs to the NDJSON (https://github.com/ndjson/ndjson-spec) (newline delimited JSON) standard format.

Specifying file format options

Individual file format options can be specified in any of the following places:

  • In the definition of a table.

  • In the definition of a named stage. For more information, see CREATE STAGE.

  • Directly in a COPY INTO <location> command when unloading data.

In addition, to simplify data unloading, Snowflake supports creating named file formats, which are database objects that encapsulate all of the required format information. Named file formats can then be used as input in all the same places where you can specify individual file format options, thereby helping to streamline the data unloading process for similarly-formatted data.

Named file formats are optional, but are recommended when you plan to regularly unload similarly-formatted data.

Creating a named file format

You can create a file format using either the web interface or SQL:

Classic Console:

Click on Databases Databases tab » <db_name> » File Formats

SQL:

CREATE FILE FORMAT

For detailed descriptions of all the file format options, see CREATE FILE FORMAT.

Examples

The following example creates a named CSV file format with a specified field delimiter:

CREATE OR REPLACE FILE FORMAT my_csv_unload_format
  TYPE = 'CSV'
  FIELD_DELIMITER = '|';
Copy

The following example creates a named JSON file format:

CREATE OR REPLACE FILE FORMAT my_json_unload_format
  TYPE = 'JSON';
Copy
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