Let's suppose I need to check by a key if the specified entity exists
in the datastore. What is the most proper way to achieve that?I have
the next ways:
1) datastoreservice.get(key).
2) execute keys-only query with the __key__ property: new
Query("Kind").addFilter(Entity.KEY_RESERVED_PROPERTY,
FilterOperator.EQUAL, key).setKeysOnly()
3) execute keys-only query with the ancestor key: new
Query("Kind").setAncestor(key).setKeysOnly()
I think that 2) or 3) is more efficient than 1) because we don't need
to deserialize the whole entity from the datastore, just get only
keys. But I don't have any suggestions about: 2) or 3) is more
efficient?
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