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52 lines
1.2 KiB
Markdown
52 lines
1.2 KiB
Markdown
## udf_sharding_hash.so使用手册
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### 1 工具介绍
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在MySQL实例，使用udf_sharding_hash.so创建函数。通过这个函数，可以算出记录所在桶号。
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### 2 工具用法
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查询MySQL plugin_dir：
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```
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mysql> show variables like 'plugin_dir';
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+---------------+--------------------------+
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| Variable_name | Value |
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+---------------+--------------------------+
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| plugin_dir | /usr/lib64/mysql/plugin/ |
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+---------------+--------------------------+
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```
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将udf_sharding_hash.so包上传至/usr/lib64/mysql/plugin/目录
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创建MySQL函数：
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```
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mysql> create function sharding_hash returns integer soname 'udf_sharding_hash.so';
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```
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删除MySQL函数：
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```
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mysql> drop function sharding_hash;
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```
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使用方法：
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```
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select sharding_hash('col_value',X);
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```
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col_value为列值，X为分片表桶的数量，与sharding.json文件'"num": X' 中的X含义一致。
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具体使用例子：
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```
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mysql> select sharding_hash('test',4);
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+-------------------------+
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| sharding_hash('test',4) |
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+-------------------------+
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| 2 |
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+-------------------------+
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mysql> select sharding_hash(123,4);
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+----------------------+
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| sharding_hash(123,4) |
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+----------------------+
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| 3 |
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+----------------------+
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```
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