# bytea type
Expresses a Unicode string
The `bytea` data type allows the storage of [binary strings](https://www.postgresql.org/docs/9.0/datatype-binary.html) or what is typically thought of as "raw bytes". Materialize supports both the typical formats for input and output: the hex format and the historical PostgreSQL escape format. The hex format is preferred.

Hex format strings are preceded by `\x` and escape format strings are preceded by `\`.

For more information about `bytea`, see the [PostgreSQL binary data type documentation](https://www.postgresql.org/docs/13/datatype-binary.html#id-1.5.7.12.9).

Detail | Info
-------|------
**Quick Syntax** | `'\xDEADBEEF'` (hex),  `'\000'` (escape)
**Size** | 1 or 4 bytes plus the actual binary string
**Catalog name** | `pg_catalog.bytea`
**OID** | 17

## Syntax

### Hex format



```mzsql
'\x<binary_string>'

```

| Syntax element | Description |
| --- | --- |
| `'\x<binary_string>'` | A hex-formatted binary string. The string is preceded by `\x` followed by hexadecimal digits. In some cases, the initial backslash may need to be escaped by doubling it (`\\`).  |


In some cases, the initial backslash may need to be escaped by doubling it (`\\`). For more information, see the PostgreSQL documentation on [string constants](https://www.postgresql.org/docs/13/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS).

### Escape format



```mzsql
'\<binary_string>'

```

| Syntax element | Description |
| --- | --- |
| `'\<binary_string>'` | An escape-formatted binary string. The string is preceded by `\`. Octet values can be escaped by converting them into their three-digit octal values and preceding them with backslashes; the backslash itself can be escaped as a double backslash. Certain values must be escaped: zero octet (`\000`), single quote (`\047` or `''''`), backslash (`\134` or `\\`), and non-printable octets (`\xxx` where `xxx` is the octal value).  |


In the escape format, octet values can be escaped by converting them into their three-digit octal values and preceding them with backslashes; the backslash itself can be escaped as a double backslash. While any octet value *can* be escaped, the values in the table below *must* be escaped.

Decimal octet value | Description | Escaped input representation | Example | Hex representation
------------|--------|----|-----------|----
0  | zero octet | `'\000'` | `'\000'::bytea` | `\x00`
39  | single quote |`''''` or `'\047'` | `''''::bytea` | `\x27`
92  | backslash | `'\\' or '\134'` | `'\\'::bytea` | `\x5c`
0 to 31 and 127 to 255  | "non-printable" octets | `'\xxx'` (octal value) | `'\001'::bytea` | `\x01`

## Details

### Valid casts

#### From `bytea`

You can [cast](../../functions/cast) `bytea` to [`text`](../text) by assignment.

> **Warning:** Casting a `bytea` value to `text` unconditionally returns a
> [hex-formatted](#hex-format) string, even if the byte array consists entirely of
> printable characters. See [handling character data](#handling-character-data)
> for alternatives.


#### To `bytea`

You can explicitly [cast](../../functions/cast) [`text`](../text) to `bytea`.

### Handling character data

Unless a `text` value is a [hex-formatted](#hex-format) string, casting to
`bytea` will encode characters using UTF-8:

```mzsql
SELECT 'hello 👋'::bytea;
```
```text
         bytea
------------------------
 \x68656c6c6f20f09f918b
```

The reverse, however, is not true. Casting a `bytea` value to `text` will not
decode UTF-8 bytes into characters. Instead, the cast unconditionally produces a
[hex-formatted](#hex-format) string:

```mzsql
SELECT '\x68656c6c6f20f09f918b'::bytea::text
```
```text
           text
----------------------------
 \x68656c6c6f2c20776f726c6
```

To decode UTF-8 bytes into characters, use the
[`convert_from`](../../functions#convert_from) function instead of casting:

```mzsql
SELECT convert_from('\x68656c6c6f20f09f918b', 'utf8') AS text;
```
```mzsql
  text
---------
 hello 👋
```

## Examples


```mzsql
SELECT '\xDEADBEEF'::bytea AS bytea_val;
```
```nofmt
 bytea_val
---------
 \xdeadbeef
```

<hr>

```mzsql
SELECT '\000'::bytea AS bytea_val;
```
```nofmt
   bytea_val
-----------------
 \x00
```