Software Development

Storing a String larger than 1500 bytes in Google Cloud Datastore with Java

Just a quick one in case this saves someone some time. If you’re used to using Google Cloud Datastore with Google App Engine (in Java), then you know that large string values are passed into the App Engine Datastore API using the Text type. But, if you’re using the gcloud libraries instead (, you don’t have this option. Strings are passed into the entity builder as String objects, or as StringValue objects. E.g.:

So, what do you do when you need to store a String larger than 1500 bytes? It turns out that the Datastore itself sets the 1500-byte limit for indexed properties. You can add a String up to 1MB in size if you explicitly set the property to be unindexed. The Text type in the App Engine libraries is essentially a facade for an unindexed String value.

In order to set an unindexed property in your Java code, you need to define your String as a object, and set it to be excluded from indexes. Then, pass the StringValue into your entity builder, and you’re good to go:

I saw some answers on how to do this with Node.js, but I had to look up the javadoc for StringValue.Builder to sort this out in the Java libraries.

It’s worth noting that it’s a good practice to set properties as unindexed if you’re not actually going to use them in any Datastore queries, to improve performance and reduce Datastore-related costs. #

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