使用自定义ID的相关成本是多少？它会以任何显着的方式影响查找时间,写入时间等吗？
解决方法
假设“shortid”的格式将存储为字符串,我认为Abigail Watson到similar question on Google Groups的响应总结了一些较大的点.她的回答主要针对Meteor应用程序,因此她的一些优点与Meteor团队的设计决策有关,但您可以看到您应该如何考虑是否使用ObjectId或“shortid”是一个基于应用的决策.
她的全部回应：
ObjectId Pros
- it has an embedded timestamp in it.
- it’s the default Mongo _id type; ubiquitous
- interoperability with other apps and drivers
ObjectId Cons
- it’s an object,and a little more difficult to manipulate in practice.
- there will be times when you forget to wrap your string in new ObjectId()
- it requires server side object creation to maintain _id uniqueness
- which makes generating them client-side by minimongo problematic
String Pros
- developers can create domain specific _id topologies
String Cons
- developer has to ensure uniqueness of _ids
- findAndModify() and getNextSequence() queries may be invalidated
Meteor’s choice to go with a string,as I understand it,basically boils down to latency compensation and being able to generate the _id on the client-side in mini-mongo. The default ObjectId implementation didn’t lend itself to being generated on the client as part of the latency compensation framework,so they decided to roll their own _id scheme.
Personally,I find the embedded timestamps in ObjectIds to be invaluable later in an application’s lifecycle. They are more difficult to manipulate,and they add more debugging time to an application’s development cycle. But for the extra 10 or 20 hours you put into debugging the ObjectIds,can return 10x or 100x savings down the road. Example: at work,we just salvaged a year’s worth of production data because of the embedded timestamps,which has saved us probably hundreds of thousands of dollars of R&D time and effort.
ObjectId’s are great if you can ensure that there’s one central authority for generating them. They’re also the preferred index type for any type of timeseries data. And while it may seem tempting to try to make a one-or-the-other decision for your entire app,I find choosing a string vs ObjectId (vs some other index scheme) really boils down to the topology of the data in the collection.
Some useful questions to maybe ask when choosing the _id for a collection:
- Does the data in the collection need latency compensation?
- Is it time-series data?
- Will other applications or worker utilities be accessing the collection?
- What is the topology of the data in the collection?
https://groups.google.com/d/msg/meteor-talk/f-ljBdZOwPk/oQYZQxCAKN8J
我投入混合的两分钱是考虑使用“shortid”的主要原因是为了更短的URL,为什么不创建一个也被索引并仅用于获取具有URL id的文档的URL属性？您可以保留ObjectId,这样您就不必担心分片或依赖性问题,同时还具有较短的URL ID值.
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