BYTEA data type

This topic describes the Firebolt implementation of the BYTEA data type.

Not all functions support the BYTEA data type currently. For more information, see BYTEA functions

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Overview

The BYTEA data type is a variable length binary string data type, commonly used to store binary data, like images, other multimedia files, or raw bytes of information. A binary string is a sequence of bytes - unlike TEXT, there is no character set. The BYTEA data type is nullable.

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Type conversions

The BYTEA type can be cast to and from the TEXT data type. A cast from BYTEA to TEXT will interpret the binary string to a hexadecimal representation with \x as a prefix. For example SELECT 'a'::BYTEA::TEXT returns \x61.

Cast from TEXT to BYTEA supports two formats, hex and escaped:

Hex
Using hex format, the TEXT type data must start with \x. Characters \n, \t, \r and ’ ’ are ignored if they are not in sequence of two characters representing one byte. Each character must be in one of the following ranges: a-f, A-F, 0-9.
Characters must be in pairs. For example, \x aa is a valid hex format, but \xa a is invalid.

Escape
Using escape format, an escaped backslash becomes just a single backslash: \\ -> \. One backslash must be followed by 3 numbers representing octal value (base 8) in range of 000-377. For example, a \375

In addition to casting, the ENCODE and DECODE functions can be used to represent TEXT as BYTEA and vice versa, but will behave slightly differently. For example, SELECT ENCODE('1'::BYTEA, 'HEX'); returns 31, while SELECT CAST('1'::BYTEA as TEXT); returns \x31, both of type TEXT.

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Comparison operator

The BYTEA comparison operator will work as lexicographical comparison but with bytes. Two empty BYTEA type expressions are equal. If two BYTEA type expressions have equivalent bytes and are of the same length, then they are equal. In a greater than (>) or less than (<) comparison, two BYTEA type expressions are compared byte by byte, and the first mismatching byte defines which is greater or less than the other.

Examples:

SELECT '\xa3'::BYTEA > '\xa2'::BYTEA; returns TRUE.

SELECT '\xa3'::BYTEA = '\xa300'::BYTEA; returns FALSE.

SELECT '\xa3'::BYTEA < '\xa300'::BYTEA; returns TRUE.

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Literal string interpretation

Literal strings will be interpreted according to the setting standard_conforming_strings, which controls whether strings are parsed with or without escaping. Similar to CAST from TEXT to BYTEA, the two text formats hex and escape are supported.

Examples:

SET standard_conforming_strings = false;
SELECT '\x3132'::BYTEA; -> '\x313332'
SELECT '\x31   32  '::BYTEA; -> '\x3120202033322020'
SELECT 'a b\230a'::BYTEA; -> '\x61206232333061'

set standard_conforming_strings = true;
SELECT '\x3132'::BYTEA; -> '\x3132'
SELECT '\x31   32  '::BYTEA; -> '\x3132'
SELECT 'a b\230a'::BYTEA; -> '\x6120629861'

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Output format

The output format for BYTEA is the hexadecimal representation of the bytes in lower case prefixed by \x (Note: in JSON \ is escaped).

Example:

SELECT 'a'::BYTEA;

Returns:

{
    "data":
    [
        ["\\x61"]
    ]
}

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Importing BYTEA from external source

The input format for importing binary data from an external source depends on the external file format.

For ORC or PARQUET files: For a specific field type without annotation (UTF-8 for example): BYTE_ARRAY (binary), bytes will be imported exactly as they are in the source. All the other types will be imported to the corresponding datatype (for example, BYTE_ARRAY with UTF-8 annotation will be imported to TEXT data type) and then cast to type BYTEA.

For CSV, TSV, or JSON files: The input data are read exactly as they are in the source, and then cast to data type BYTEA.

CSV File Example:

file

'row1'
'a�a'
'\xaabf'
15
'15'

SQL

CREATE EXTERNAL TABLE ex_table
(
    column1 BYTEA
) URL = 's3://...'
  OBJECT_PATTERN = '...'
  TYPE = (CSV);

SELECT * FROM ex_table;

Returns:

| column1    |
| ---------- |
| \x726f7731 |
| \x61ff61   |
| \xaabf     |
| \x3135     |
| \x3135     |