5: Embed “point-in-time” data

原文如下：

 

 

As mentioned in the orders example in "Tip #1:Duplicate data for speed,reference data for integrity" on page 1,you don't actually want the information in the order to change if a product,say,goes on sale or  gets a new thumbnail.Any sort of information like this,where you want to snapshot the data at a particular time,should be embedded.

 

Another example from the order document:the address fields also fall into the"point-in-time"category of data.You don't want a user's past orders to change if he updatas his profile

 

嵌入那些具有时效点的数据，会随着时间变化的数据，这里例子里就是订单中的收获地址与目前用户的地址分开