问题
Is there any limit on the number of Entity Kinds you can have in App Engine?
The low level datastore ShardedCounter.java example creates a new Entity Kind for each counter name whereas the JDO example stores each counter in the same Entity Kind. I like the advantage of the former, but don't know whether it scales to millions of counter names?
回答1:
The datastore basically works as giant HashMap<Key-Entity>, as the HashMap you can put unlimited numbers of key, since one key is a mix of your appId, Kind, and entity Id or name you can use unlimited number of kinds too.
回答2:
There's no reason why GAE would impose such a restriction, having a new kind doesn't affect special things.
So there's no such limit.
We should be able to find it on Google if it exists.
来源：https://stackoverflow.com/questions/12536958/entity-kind-quota-limit-in-app-engine