What is the best/fastest way to check if an Entity exists in a google-app-engine datastore? For now I'm trying to get the entity by key and checking if the get() returns an error.
I don't know the process of getting an Entity on the datastore. Is there a faster way for doing only this check?
com.google.appengine.api has been deprecated in favor of the App Engine GCS client.
Have you considered using a query? Guess-and-check is not a scalable way to find out of an entity exists in a data store. A query can be created to retrieve entities from the datastore that meet a specified set of conditions:
https://developers.google.com/appengine/docs/java/datastore/queries
EDIT:
What about the key-only query? Key-only queries run faster than queries that return complete entities. To return only the keys, use the Query.setKeysOnly() method.
new Query("Kind").addFilter(Entity.KEY_RESERVED_PROPERTY, FilterOperator.EQUAL, key).setKeysOnly();
Source: [1]: http://groups.google.com/group/google-appengine-java/browse_thread/thread/b1d1bb69f0635d46/0e2ba938fad3a543?pli=1