> ## 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.

# Native protocol column types

> Column types for the native protocol

See [Data Types](/reference/data-types/index) for general reference.

<Tip>
  Numeric types encoding matches memory layout of little endian CPUs like AMD64 or ARM64, allowing very efficient encoding and decoding.
</Tip>

| Type                                                        | Encoding                                                                                                                                       |
| ----------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- |
| **Integers** ([Int/UInt](/reference/data-types/int-uint))   | 8, 16, 32, 64, 128 or 256 bits in little endian                                                                                                |
| **Floats** ([Float32/Float64](/reference/data-types/float)) | IEEE 754 binary representation                                                                                                                 |
| [String](/reference/data-types/string)                      | Array of strings as (len, value)                                                                                                               |
| [FixedString(N)](/reference/data-types/fixedstring)         | Array of N-byte sequences                                                                                                                      |
| [IPv4](/reference/data-types/ipv4)                          | Alias of `UInt32`, represented as UInt32                                                                                                       |
| [IPv6](/reference/data-types/ipv6)                          | Alias of `FixedString(16)`, represented as binary                                                                                              |
| [Tuple](/reference/data-types/tuple)                        | Array of columns encoded continuously. Example: `Tuple(String, UInt8)` = two continuous columns                                                |
| [Map](/reference/data-types/map)                            | `Map(K, V)` = three columns: `Offsets ColUInt64, Keys K, Values V`. Row count in Keys/Values = last Offsets value                              |
| [Array](/reference/data-types/array)                        | `Array(T)` = two columns: `Offsets ColUInt64, Data T`. Row count in Data = last Offsets value                                                  |
| [Nullable](/reference/data-types/nullable)                  | `Nullable(T)` = two columns: `Nulls ColUInt8, Values T` with same row count. Nulls is mask: 1=null, 0=value                                    |
| [UUID](/reference/data-types/uuid)                          | Alias of `FixedString(16)`, represented as binary                                                                                              |
| [Enum](/reference/data-types/enum)                          | Alias of `Int8` or `Int16`, each integer mapped to a String value                                                                              |
| [LowCardinality](/reference/data-types/lowcardinality)      | `LowCardinality(T)` = two columns: `Index T, Keys K` where K is UInt8/16/32/64. Index contains unique values, Keys contains indexes into Index |
| [Bool](/reference/data-types/boolean)                       | Alias of `UInt8`: 0=false, 1=true                                                                                                              |

**Example: Nullable encoding**

```text theme={null}
To encode [null, "", "hello", null, "world"]:
  Values: ["", "", "hello", "", "world"] (len: 5)
  Nulls:  [ 1,  0,       0,  1,       0] (len: 5)
```

**Example: LowCardinality encoding**

```text theme={null}
To encode ["Eko", "Eko", "Amadela", "Amadela", "Amadela", "Amadela"]:
  Index: ["Eko", "Amadela"] (String)
  Keys:  [0, 0, 1, 1, 1, 1] (UInt8)
```