如何实现“自动增量”在Google AppEngine上 [英] How to implement "autoincrement" on Google AppEngine

问题描述

我必须以强单调增加的方式标记一些东西。

I have to label something in a "strong monotone increasing" fashion. Be it Invoice Numbers, shipping label numbers or the like.

1. 一个号码不得使用两次


2. 每个数字都应该在所有较小的数字被使用（无孔）时使用。

计数1,2,3,4 ...
我可用的数字空间通常是100.000个数字，我每天需要1000个。

Fancy way of saying: I need to count 1,2,3,4 ... The number Space I have available are typically 100.000 numbers and I need perhaps 1000 a day.

我知道这是一个困难在分布式系统中的问题，通常我们更好地与GUID。

I know this is a hard Problem in distributed systems and often we are much better of with GUIDs. But in this case for legal reasons I need "traditional numbering".

这可以在Google AppEngine（最好是Python）上实现吗？

Can this be implemented on Google AppEngine (preferably in Python)?

推荐答案

如果你绝对必须有没有间隙的顺序增加数字，你需要使用一个实体，你在事务中更新每个新号码。在实践中，你会受到限制，每秒生成大约1-5个数字 - 这听起来可以满足你的要求。

If you absolutely have to have sequentially increasing numbers with no gaps, you'll need to use a single entity, which you update in a transaction to 'consume' each new number. You'll be limited, in practice, to about 1-5 numbers generated per second - which sounds like it'll be fine for your requirements.

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