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A table-valued function (TVF) that reads CSV files from Amazon S3. The function can use either a location object (recommended) or direct credentials to access the data. READ_CSV returns a table with data from the specified CSV file, where each cell is read as TEXT.
Syntax
-- Using LOCATION object (recommended)
READ_CSV (
LOCATION => 'location_name'
[, PATTERN => <pattern>]
[, COMPRESSION => <file_compression>]
[, HEADER => { TRUE | FALSE }]
[, DELIMITER => <field_delimiter>]
[, QUOTE => { "'" | '"' | SINGLE_QUOTE | DOUBLE_QUOTE}]
[, NULL_STRING => <null_string>]
[, ESCAPE => <escape_character>]
[, SKIP_BLANK_LINES => { TRUE | FALSE }]
[, EMPTY_FIELD_AS_NULL => { TRUE | FALSE }]
[, INFER_SCHEMA => { TRUE | FALSE }]
)
|
-- Using static credentials
READ_CSV (
URL => <url>
[, COMPRESSION => <file_compression>]
[, AWS_ACCESS_KEY_ID => <aws_access_key_id>]
[, AWS_SECRET_ACCESS_KEY => <aws_secret_access_key>]
[, AWS_SESSION_TOKEN => <aws_session_token>]
[, AWS_ROLE_ARN => <aws_role_arn>]
[, AWS_ROLE_EXTERNAL_ID => <aws_role_external_id>]
[, HEADER => { TRUE | FALSE }]
[, DELIMITER => <field_delimiter>]
[, QUOTE => { "'" | '"' | SINGLE_QUOTE | DOUBLE_QUOTE}]
[, NULL_STRING => <null_string>]
[, ESCAPE => <escape_character>]
[, SKIP_BLANK_LINES => { TRUE | FALSE }]
[, EMPTY_FIELD_AS_NULL => { TRUE | FALSE }]
[, INFER_SCHEMA => { TRUE | FALSE }]
)
Parameters
| Parameter | Description | Supported input types |
|---|
| LOCATION | The name of a location object that contains the Amazon S3 URL and credentials. Firebolt recommends using LOCATION to store credentials for authentication . LOCATION must be specified as a string literal (e.g., LOCATION => 'my_location'). Unlike URL, it cannot be used as a positional parameter. For a comprehensive guide, see LOCATION objects. | TEXT |
PATTERN | When using LOCATION, an optional glob pattern to filter files within the location’s URL path. The pattern is applied relative to the location’s base path. For example, PATTERN => 'week_1/*.csv' will match all .csv files in the week_1 subdirectory. | TEXT |
URL | The location containing your files in an Amazon S3 bucket. The expected format is s3://{bucket_name}/{full_file_path_glob_pattern}. | TEXT |
COMPRESSION | The compression type of the input file. If compression is not set, compression is inferred from the file extension. | TEXT |
AWS_ACCESS_KEY_ID | The AWS access key ID. | TEXT |
AWS_SECRET_ACCESS_KEY | The AWS secret access key. | TEXT |
AWS_SESSION_TOKEN | The AWS session token. | TEXT |
AWS_ROLE_ARN | The AWS role arn. | TEXT |
AWS_ROLE_EXTERNAL_ID | The AWS role external ID. | TEXT |
HEADER | Set to TRUE if the first row of the CSV file contains a header row containing the column names. | BOOL |
DELIMITER | Specify the character used to separate fields. The default delimiter is a comma (,). | TEXT |
QUOTE | Specify the character used for quoting fields. The default is double quote ("). If a single quote is specified, the quote character will be set to ('). Accepts only DOUBLE_QUOTE, SINGLE_QUOTE, ', or ". | TEXT |
NULL_STRING | Specify the string used to represent NULL values. The default is an empty string, which means that empty strings are interpreted as NULL values. | TEXT |
ESCAPE | Specify the character used to escape special characters. The default character is the quote (') character. | TEXT |
SKIP_BLANK_LINES | Set to TRUE to ignore blank lines in the file. | BOOL |
EMPTY_FIELD_AS_NULL | Specify whether empty fields should be interpreted as NULL values. The default is TRUE. If set to FALSE, empty fields are interpreted as empty strings. | BOOL |
INFER_SCHEMA | Specify whether column data types should be inferred from the data, instead of using TEXT. | BOOL |
Return Type
The result is a table with the data from the CSV file. Each cell is read as a TEXT.
When loading multiple files, Firebolt infers the schema from the most recently modified file. The remaining files must have compatible data types. If types vary between files (e.g., a column contains integers in one file but doubles in another, or is numeric in one file but text in another), the inferred schema may not match all files and thus cause data type errors or query failures. In such cases, we recommend defining an explicit schema using either external tables or COPY FROM into existing tables. Examples
Using LOCATION object
Best practice
Firebolt recommends using a LOCATION object to store credentials for authentication.
When using READ_CSV(), the URL parameter in the location should contain only CSV files (see location table-valued functions).
The following code example reads a CSV file from the location specified by my_csv_location, treating the first row as a header containing column names:
SELECT * FROM READ_CSV(
LOCATION => 'my_csv_location',
HEADER => true
);
PATTERN parameter with a location object to filter specific files:
CREATE LOCATION firebolt_sample_dataset WITH
SOURCE = AMAZON_S3
URL = 's3://firebolt-publishing-public/help_center_assets/firebolt_sample_dataset/';
SELECT $source_file_name, "Name", "LevelType" FROM READ_CSV(
LOCATION => 'firebolt_sample_dataset', PATTERN => 'levels*',
HEADER => true
) limit 5;
| $source_file_name | Name | LevelType |
|---|
| help_center_assets/firebolt_sample_dataset/levels.csv | Thunderbolt Circuit | FastestLap |
| help_center_assets/firebolt_sample_dataset/levels.csv | Velocity Vale | FirstToComplete |
| help_center_assets/firebolt_sample_dataset/levels.csv | Raceway Ridge | FastestLap |
| help_center_assets/firebolt_sample_dataset/levels.csv | Nitro Narrows | FirstToComplete |
| help_center_assets/firebolt_sample_dataset/levels.csv | Thunder Road | FirstToComplete |
levels* within the location’s base path, showing specific columns and the source file for verification.
Using static credentials
SELECT * FROM READ_CSV(
URL => 's3://firebolt-publishing-public/help_center_assets/firebolt_sample_dataset/levels.csv',
HEADER => true
);
url can represent a single file or a glob pattern. If a glob pattern is used, all files matching the pattern will be read. A special column $source_file_name can be used to identify the source file of each row in the result set:
SELECT *, $source_file_name FROM READ_CSV(
URL => 's3://firebolt-publishing-public/help_center_assets/firebolt_sample_dataset/*.csv',
HEADER => TRUE
);
*) can only be used at the end of the path. You can use it with any text before or after, such as *.csv, date=2025*.csv, or data_*.csv.
The pattern will recursively match files in all subdirectories. For example:
SELECT * FROM READ_CSV('s3://firebolt-publishing-public/*.csv')
help_center_assets/firebolt_sample_dataset/*.csv.
Example
In the following example, the URL is set as the first positional parameter and reads a CSV file:
SELECT * FROM READ_CSV('s3://firebolt-publishing-public/help_center_assets/firebolt_sample_dataset/levels.csv');
| f0 | f1 | f2 | f3 | f4 | f5 | f6 | f7 | f8 | … |
|---|
| LevelID | GameID | Level | Name | LevelType | NextLevel | MinPointsToPass | MaxPoints | NumberOfLaps | … |
| 1 | 1 | 1 | Thunderbolt Circuit | FastestLap | 2 | 5 | 20 | 5 | … |
| 2 | 1 | 2 | Velocity Vale | FirstToComplete | 3 | 15 | 30 | 10 | … |
| 3 | 1 | 3 | Raceway Ridge | FastestLap | 4 | 25 | 40 | 20 | … |
| 4 | 1 | 4 | Nitro Narrows | FirstToComplete | 5 | 60 | 100 | 10 | … |
| 5 | 1 | 5 | Thunder Road | FirstToComplete | 6 | 80 | 150 | 15 | … |
| 6 | 1 | 6 | Burnout Boulevard | Drift | 7 | 50 | 80 | 8 | … |
| 7 | 1 | 7 | Speed Street | FastestLap | 8 | 40 | 70 | 7 | … |
| 8 | 1 | 8 | Racing Ravine | FastestLap | 9 | 60 | 100 | 20 | … |
| 9 | 1 | 9 | Drift District | Drift | 10 | 100 | 250 | 25 | … |
| 10 | 1 | 10 | Acceleration Alley | FirstToComplete | null | 200 | 500 | 50 | … |
URL as a named parameter and reads a CSV file with column names in the first row:
SELECT * FROM READ_CSV(URL => 's3://firebolt-publishing-public/help_center_assets/firebolt_sample_dataset/levels.csv',
HEADER => true);
| LevelID | GameID | Level | Name | LevelType | NextLevel | MinPointsToPass | MaxPoints | NumberOfLaps | … |
|---|
| 1 | 1 | Thunderbolt Circuit | FastestLap | 2 | 5 | 20 | 5 | 20 | … |
| 2 | 1 | Velocity Vale | FirstToComplete | 3 | 15 | 30 | 10 | 10 | … |
| 3 | 1 | Raceway Ridge | FastestLap | 4 | 25 | 40 | 20 | 20 | … |
| 4 | 1 | Nitro Narrows | FirstToComplete | 5 | 60 | 100 | 10 | 10 | … |
| 5 | 1 | Thunder Road | FirstToComplete | 6 | 80 | 150 | 15 | 15 | … |
| 6 | 1 | Burnout Boulevard | Drift | 7 | 50 | 80 | 8 | 8 | … |
| 7 | 1 | Speed Street | FastestLap | 8 | 40 | 70 | 7 | 7 | … |
| 8 | 1 | Racing Ravine | FastestLap | 9 | 60 | 100 | 20 | 20 | … |
| 9 | 1 | Drift District | Drift | 10 | 100 | 250 | 25 | 25 | … |
| 10 | 1 | Acceleration Alley | FirstToComplete | null | 200 | 500 | 50 | 50 | … |
NULL values:
SELECT * FROM READ_CSV(URL => 's3://firebolt-publishing-public/help_center_assets/firebolt_sample_dataset/levels.csv',
HEADER => true, EMPTY_FIELD_AS_NULL => false);
| LevelID | GameID | Level | Name | LevelType | … |
|---|
| 1 | 1 | Thunderbolt Circuit | FastestLap | 2 | … |
| 2 | 1 | Velocity Vale | FirstToComplete | 3 | … |
| 3 | 1 | Raceway Ridge | FastestLap | 4 | … |
| 4 | 1 | Nitro Narrows | FirstToComplete | 5 | … |
| 5 | 1 | Thunder Road | FirstToComplete | 6 | … |
| 6 | 1 | Burnout Boulevard | Drift | 7 | … |
| 7 | 1 | Speed Street | FastestLap | 8 | … |
| 8 | 1 | Racing Ravine | FastestLap | 9 | … |
| 9 | 1 | Drift District | Drift | 10 | … |
| 10 | 1 | Acceleration Alley | FirstToComplete | | … |
URL as a named parameter, reads a CSV file with column names in the first row, and infers types for all columns. In this example it allows filtering using numeric comparisons, since the MaxPoints and MinPointsToPass columns are properly typed as numbers rather than strings:
SELECT * FROM READ_CSV(URL => 's3://firebolt-publishing-public/help_center_assets/firebolt_sample_dataset/levels.csv',
HEADER => true, INFER_SCHEMA => true) WHERE "MaxPoints" > 2 * "MinPointsToPass";
| LevelID | GameID | Level | Name | LevelType | NextLevel | MinPointsToPass | MaxPoints | NumberOfLaps | … |
|---|
| 1 | 1 | Thunderbolt Circuit | FastestLap | 2 | 5 | 20 | 5 | 20 | … |
| 9 | 1 | Drift District | Drift | 10 | 100 | 250 | 25 | 25 | … |
| 10 | 1 | Acceleration Alley | FirstToComplete | null | 200 | 500 | 50 | 50 | … |
