确定你的3nf关系的主键和外部键。

Identify the primary and foreign keys in your 3nf relations.

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非规范化设计减少了查询操作所需的连接，减少了外部键和索引的数量，可以预先进行统计计算，提高了查询时的响应速度；

While abnormalization design reduces joins which query requires and the number of keys and indices, can count in advance and improve the query speed.

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当调用导出的键不安全的函数时，这个处理将增加相应的开销，但是仅当被调用的函数位于调用模块外部的时候才会出现这种情况。

This processing adds overhead when an exported key-unsafe function is called, but only when the called function is external to the calling module.

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