Google App Engine (datastore) - will a deleted key

Question

I've got a simple question about datastore keys. If I delete an entity, is there any possibility that the key will be created again? or each key is unique and can be generated only one-time?

Thanks.

Answer 1

It is definitely possible to re-use keys.

Easy to test, for example using the datastore admin page:

• create an entity for one of your entity models using a custom/specified key name and some property values
• delete the entity
• create another one using the same key name and different property values...

As for the keys with auto-generated IDs it is theoretically possible, but I guess rather unlikely due to the high number of possibilities. From Assigning identifiers:

Cloud Datastore can be configured to generate auto IDs using two different auto id policies:

• The default policy generates a random sequence of unused IDs that are approximately uniformly distributed. Each ID can be up to 16 decimal digits long.
• The legacy policy creates a sequence of non-consecutive smaller integer IDs.