GAE Go版本3 API错误

I'm attempting to update a pretty trivial web-app to version 3 of Go GAE. I get this error whenever I query the datastore for a specific object that I know is there, but other queries seem to fail silently. Has the way you use the datastore changed (function parameters excluded - my new code does compile!)?

Error = API error 4 (datastore_v3: NEED_INDEX): no matching index found.

Thanks

You're attempting to execute a query that requires a custom index, but you haven't specified one (or it hasn't finished building). You should fully exercise your app on your local dev_appserver, then upload your app to update the index definitions.