ClickHouse/docs/en/data_types/domains/ipv6.md

## IPv6

`IPv6` is a domain based on `FixedString(16)` type and serves as typed replacement for storing IPv6 values.  It provides compact storage with human-friendly input-output format, and column type information on inspection.

### Basic Usage

```sql
CREATE TABLE hits (url String, from IPv6) ENGINE = MergeTree() ORDER BY url;

DESCRIBE TABLE hits;
```

```text
┌─name─┬─type───┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┐
│ url  │ String │              │                    │         │                  │
│ from │ IPv6   │              │                    │         │                  │
└──────┴────────┴──────────────┴────────────────────┴─────────┴──────────────────┘
```

OR you can use `IPv6` domain as a key:

```sql
CREATE TABLE hits (url String, from IPv6) ENGINE = MergeTree() ORDER BY from;
```

`IPv6` domain supports custom input as IPv6-strings:

```sql
INSERT INTO hits (url, from) VALUES ('https://wikipedia.org', '2a02:aa08:e000:3100::2')('https://clickhouse.yandex', '2001:44c8:129:2632:33:0:252:2')('https://clickhouse.yandex/docs/en/', '2a02:e980:1e::1');

SELECT * FROM hits;
```

```text
┌─url────────────────────────────────┬─from──────────────────────────┐
│ https://clickhouse.yandex          │ 2001:44c8:129:2632:33:0:252:2 │
│ https://clickhouse.yandex/docs/en/ │ 2a02:e980:1e::1               │
│ https://wikipedia.org              │ 2a02:aa08:e000:3100::2        │
└────────────────────────────────────┴───────────────────────────────┘
```

Values are stored in compact binary form:

```sql
SELECT toTypeName(from), hex(from) FROM hits LIMIT 1;
```

```text
┌─toTypeName(from)─┬─hex(from)────────────────────────┐
│ IPv6             │ 200144C8012926320033000002520002 │
└──────────────────┴──────────────────────────────────┘
```

Domain values are not implicitly convertible to types other than `FixedString(16)`.
If you want to convert `IPv6` value to a string, you have to do that explicitly with `IPv6NumToString()` function:

```sql
SELECT toTypeName(s), IPv6NumToString(from) as s FROM hits LIMIT 1;
```

```text
┌─toTypeName(IPv6NumToString(from))─┬─s─────────────────────────────┐
│ String                            │ 2001:44c8:129:2632:33:0:252:2 │
└───────────────────────────────────┴───────────────────────────────┘
```

Or cast to a `FixedString(16)` value:

```sql
SELECT toTypeName(i), CAST(from as FixedString(16)) as i FROM hits LIMIT 1;
```

```text
┌─toTypeName(CAST(from, 'FixedString(16)'))─┬─i───────┐
│ FixedString(16)                           │  <20><><EFBFBD> │
└───────────────────────────────────────────┴─────────┘
```

[Original article](https://clickhouse.yandex/docs/en/data_types/domains/ipv6) <!--hide-->