Unloading CSV File

Unloading CSV File

Syntax:

COPY INTO { internalStage | externalStage | externalLocation }
FROM { [<database_name>.]<table_name> | ( <query> ) }
FILE_FORMAT = (
    TYPE = CSV,
    RECORD_DELIMITER = '<character>',
    FIELD_DELIMITER = '<character>',
    COMPRESSION = gzip,
    OUTPUT_HEADER = true -- Unload with header
)
[MAX_FILE_SIZE = <num>]
[DETAILED_OUTPUT = true | false]

• More CSV options refer to CSV File Format Options
• Unloading into multiple files use the MAX_FILE_SIZE Copy Option
• More details about the syntax can be found in COPY INTO <location>

Tutorial

Step 1. Create an External Stage

CREATE STAGE csv_unload_stage 
URL = 's3://unload/csv/' 
CONNECTION = (
    ACCESS_KEY_ID = '<your-access-key-id>' 
    SECRET_ACCESS_KEY = '<your-secret-access-key>'
);

Step 2. Create Custom CSV File Format

CREATE FILE FORMAT csv_unload_format 
    TYPE = CSV,
    RECORD_DELIMITER = '\n',
    FIELD_DELIMITER = ',',
    COMPRESSION = gzip,     -- Unload with gzip compression
    OUTPUT_HEADER = true,   -- Unload with header
    SKIP_HEADER = 1;        -- Only for loading, skip first line when querying if the CSV file has header

Step 3. Unload into CSV File

COPY INTO @csv_unload_stage 
FROM (
    SELECT * 
    FROM generate_series(1, 100)
) 
FILE_FORMAT = (FORMAT_NAME = 'csv_unload_format')
DETAILED_OUTPUT = true;

Result:

┌──────────────────────────────────────────────────────────────────────────────────────────┐
│                             file_name                            │ file_size │ row_count │
├──────────────────────────────────────────────────────────────────┼───────────┼───────────┤
│   data_c8382216-0a04-4920-9eca-7b5debe3eed6_0000_00000000.csv.gz │       187 │       100 │
└──────────────────────────────────────────────────────────────────────────────────────────┘

Step 4. Verify the Unloaded CSV Files

SELECT COUNT($1)
FROM @csv_unload_stage
(
    FILE_FORMAT => 'csv_unload_format',
    PATTERN => '.*[.]csv[.]gz'
);

Result:

┌───────────┐
│ count($1) │
├───────────┤
│       100 │
└───────────┘