主键更新与主键删除+插入 [英] primary key update vs primary key deletion + insertion

问题描述

我听说有传言说，当更改主键列中的值时，应先删除行，然后再插入新值，而不要更新列.

I have heard some rumours that when value in primary key column is changed, then row should be deleted then inserted with new value rather then column just updated.

更新主键而不删除/插入主键是否会对性能产生影响?

Are there any performance implications when primary key is updated and not deleted/inserted?

推荐答案

更新主键时:

• 支持索引已更新.
• 是否为外键将被检查 给孩子们.

• the supporting index is updated.
• if it is a foreign key will be checked for childs.

但是，如果您执行删除和插入操作，则删除操作将同时执行两个操作，插入操作将更新索引.因此，进行删除和插入没有任何好处.还是我所不知道的.

But if you do a delete and an insert, for delete both points are performed and for insert the index is updated. So no gain to do a delete and an insert. Or none that I'm aware of.

很快，执行两次操作而不是一次操作会更糟.不算删除是最难的操作.

Shortly, it is worse to do two operations instead of one. Not counting that delete is the hardest operation.

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