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专门添加一个IsDeleted(bool类型)字段, DeleteTime字段只用来记录删除时间 #158

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wdydxf opened this issue Apr 30, 2020 · 2 comments

wdydxf commented Apr 30, 2020

您的功能请求与现有问题有关吗？请描述

where DeleteTime is null的效率有点差, 测试了300万条数据, 关联三个表时, 非常耗时.
查阅了相关资料, 资料说尽量不用IsNull做判断.

描述您想要的解决方案

专门添加一个IsDeleted(bool类型)字段, DeleteTime字段只用来记录删除时间

描述你考虑过的替代方案

现在的方式也可以使用

附加上下文，比如截图

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gmf520 commented Apr 30, 2020

逻辑删除涉及到唯一索引的问题，只用一个bool字段是实现不了唯一索引，因而用DateTime类型，即能表示已删除，同时也解决已删除数据的唯一索引问题
判断一个字段是否为null不应该成为性能的瓶颈吧

xuejmnet commented Jan 30, 2022

确实mysql尽可能使用非null或许使用最小时间做为删除字段判断会比isnull高效譬如>1970/01/01之类的

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