Victor Victor - 1 year ago 231
Java Question

Checking if Entity exists in google app engine datastore.

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?

Answer Source 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:


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]:

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