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Symbolic link
78 lines
3.6 KiB
Markdown
Symbolic link
78 lines
3.6 KiB
Markdown
## IPv6
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`IPv6` 是基于`FixedString(16)` 类型的domain类型，用来存储IPv6地址值。它使用紧凑的存储方式，提供用户友好的输入输出格式， 自动检查列类型。
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### 基本用法
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``` sql
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CREATE TABLE hits (url String, from IPv6) ENGINE = MergeTree() ORDER BY url;
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DESCRIBE TABLE hits;
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```
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```
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┌─name─┬─type───┬─default_type─┬─default_expression─┬─comment─┬─codec_expression─┐
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│ url │ String │ │ │ │ │
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│ from │ IPv6 │ │ │ │ │
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└──────┴────────┴──────────────┴────────────────────┴─────────┴──────────────────┘
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```
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您也可以使用 `IPv6`domain做主键:
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``` sql
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CREATE TABLE hits (url String, from IPv6) ENGINE = MergeTree() ORDER BY from;
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```
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`IPv6` domain支持定制化的IPv6地址字符串格式:
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``` sql
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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');
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SELECT * FROM hits;
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```
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```
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┌─url────────────────────────────────┬─from──────────────────────────┐
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│ https://clickhouse.yandex │ 2001:44c8:129:2632:33:0:252:2 │
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│ https://clickhouse.yandex/docs/en/ │ 2a02:e980:1e::1 │
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│ https://wikipedia.org │ 2a02:aa08:e000:3100::2 │
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└────────────────────────────────────┴───────────────────────────────┘
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```
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它以紧凑的二进制格式存储数值:
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``` sql
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SELECT toTypeName(from), hex(from) FROM hits LIMIT 1;
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```
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```
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┌─toTypeName(from)─┬─hex(from)────────────────────────┐
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│ IPv6 │ 200144C8012926320033000002520002 │
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└──────────────────┴──────────────────────────────────┘
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```
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Domain不可隐式转换为除`FixedString(16)`以外的类型。如果要将`IPv6`值转换为字符串，则必须使用`IPv6NumToString()`函数显示地进行此操作:
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``` sql
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SELECT toTypeName(s), IPv6NumToString(from) as s FROM hits LIMIT 1;
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```
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```
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┌─toTypeName(IPv6NumToString(from))─┬─s─────────────────────────────┐
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│ String │ 2001:44c8:129:2632:33:0:252:2 │
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└───────────────────────────────────┴───────────────────────────────┘
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```
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或转换为 `FixedString(16)`类型:
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``` sql
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SELECT toTypeName(i), CAST(from as FixedString(16)) as i FROM hits LIMIT 1;
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```
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```
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┌─toTypeName(CAST(from, 'FixedString(16)'))─┬─i───────┐
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│ FixedString(16) │ <20><><EFBFBD> │
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└───────────────────────────────────────────┴─────────┘
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```
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[Original article](https://clickhouse.yandex/docs/en/data_types/domains/ipv6) <!--hide-->
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