当我们需要在数据库设计中使用1对1关系时？
我们什么时候需要在数据库设计中使用1对1关系？在我看来，如果两个表是1对1的关系，他们可以组合成一个表。这是真的吗？
When do we need to use a 1-to-1 relationship in database design? In my opinion, if two tables are in a 1-to-1 relationship, they can be combined into one table. Is this true?
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大型表格的垂直分割以减少I / O，
Vertical partitioning for large tables to reduce I/O and cache requirements -- separate columns that are queried often vs rarely.
向 alter table >添加列到生产系统时， code>是太贵。
Adding a column to a production system when the alter table is "too expensive".
超级类型/子类型 模式。
Super-type/subtype pattern.
垂直分区以从表（连接）消除中受益 - 提供优化器
支持它（再次减少I / O和缓存）。
Vertical partitioning to benefit from table (join) elimination -- providing optimizer supports it (again to reduce I/O and cache) .
Anchor modeling -- similar to 4, but down to 6NF.