> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-fix-nav-issues.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Documentation for the MsgPack format

# MsgPack

| Input | Output | Alias |
| ----- | ------ | ----- |
| ✔     | ✔      |       |

<h2 id="description">
  Description
</h2>

ClickHouse supports reading and writing [MessagePack](https://msgpack.org/) data files.

<h2 id="data-types-matching">
  Data types matching
</h2>

| MessagePack data type (`INSERT`)                                   | ClickHouse data type                                                          | MessagePack data type (`SELECT`)   |
| ------------------------------------------------------------------ | ----------------------------------------------------------------------------- | ---------------------------------- |
| `uint N`, `positive fixint`                                        | [`UIntN`](/reference/data-types/int-uint)                                     | `uint N`                           |
| `int N`, `negative fixint`                                         | [`IntN`](/reference/data-types/int-uint)                                      | `int N`                            |
| `bool`                                                             | [`UInt8`](/reference/data-types/int-uint)                                     | `uint 8`                           |
| `fixstr`, `str 8`, `str 16`, `str 32`, `bin 8`, `bin 16`, `bin 32` | [`String`](/reference/data-types/string)                                      | `bin 8`, `bin 16`, `bin 32`        |
| `fixstr`, `str 8`, `str 16`, `str 32`, `bin 8`, `bin 16`, `bin 32` | [`FixedString`](/reference/data-types/fixedstring)                            | `bin 8`, `bin 16`, `bin 32`        |
| `float 32`                                                         | [`Float32`](/reference/data-types/float)                                      | `float 32`                         |
| `float 64`                                                         | [`Float64`](/reference/data-types/float)                                      | `float 64`                         |
| `uint 16`                                                          | [`Date`](/reference/data-types/date)                                          | `uint 16`                          |
| `int 32`                                                           | [`Date32`](/reference/data-types/date32)                                      | `int 32`                           |
| `uint 32`                                                          | [`DateTime`](/reference/data-types/datetime)                                  | `uint 32`                          |
| `uint 64`                                                          | [`DateTime64`](/reference/data-types/datetime)                                | `uint 64`                          |
| `fixarray`, `array 16`, `array 32`                                 | [`Array`](/reference/data-types/array)/[`Tuple`](/reference/data-types/tuple) | `fixarray`, `array 16`, `array 32` |
| `fixmap`, `map 16`, `map 32`                                       | [`Map`](/reference/data-types/map)                                            | `fixmap`, `map 16`, `map 32`       |
| `uint 32`                                                          | [`IPv4`](/reference/data-types/ipv4)                                          | `uint 32`                          |
| `bin 8`                                                            | [`String`](/reference/data-types/string)                                      | `bin 8`                            |
| `int 8`                                                            | [`Enum8`](/reference/data-types/enum)                                         | `int 8`                            |
| `bin 8`                                                            | [`(U)Int128`/`(U)Int256`](/reference/data-types/int-uint)                     | `bin 8`                            |
| `int 32`                                                           | [`Decimal32`](/reference/data-types/decimal)                                  | `int 32`                           |
| `int 64`                                                           | [`Decimal64`](/reference/data-types/decimal)                                  | `int 64`                           |
| `bin 8`                                                            | [`Decimal128`/`Decimal256`](/reference/data-types/decimal)                    | `bin 8 `                           |

<h2 id="example-usage">
  Example usage
</h2>

Writing to a file ".msgpk":

```sql theme={null}
$ clickhouse-client --query="CREATE TABLE msgpack (array Array(UInt8)) ENGINE = Memory;"
$ clickhouse-client --query="INSERT INTO msgpack VALUES ([0, 1, 2, 3, 42, 253, 254, 255]), ([255, 254, 253, 42, 3, 2, 1, 0])";
$ clickhouse-client --query="SELECT * FROM msgpack FORMAT MsgPack" > tmp_msgpack.msgpk;
```

<h2 id="format-settings">
  Format settings
</h2>

| Setting                                                                                                              | Description                                                                                    | Default |
| -------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------- | ------- |
| [`input_format_msgpack_number_of_columns`](/reference/settings/formats#input_format_msgpack_number_of_columns)       | the number of columns in inserted MsgPack data. Used for automatic schema inference from data. | `0`     |
| [`output_format_msgpack_uuid_representation`](/reference/settings/formats#output_format_msgpack_uuid_representation) | the way how to output UUID in MsgPack format.                                                  | `EXT`   |