可以对数据存储区实体使用否定ID吗？

Question

I would like to re-visit this old SO post , which says that the datastore can never have negative ID's, but is for the old M/S datastore and I believe no longer applies.

(Note that this question is distinct from the common question about the auto-generate functionality, which still does not produce negative numbers.)

I find that the consensus of SO is that the datastore does not support negative id's, yet I've been using them for one of the Kind's in my app.

I manually assign the negative numbers to the (Java) long id field of my entities' when I created them. When I view the entities in the GAE console data viewer they appear correctly as negative numbers, eg "id=-8673495404141992816".

Perhaps the idea that the DS doesn't support negative ID's is just a relic of the M/S datastore, or perhaps I have unintentionally gone into unsupported and uncharted territory - in which case I should change my app!

Also, IMO, this is a fairly fundamental question in regard to the DS, so I want to be clear about the answer. After all, I'd like to have the option to generate ID's using a 64-bit hash function which could produce negative numbers.

Answer 1

IDs appear to be 64-bit values. However, the default app id generator limits them to postive 53 bit values so that they will work with Javascript. You're probably floating around in uncharted territory.

Or at the very least, rarely used territory.