GAE - Truncating Datastore Data

At this time there were no quick truncate for the Entities. Solution: Create data script in your servlet to delete.

import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.PreparedQuery;
import com.google.appengine.api.datastore.Query;
....
@SuppressWarnings("serial")
public class GreetingServiceImpl extends RemoteServiceServlet implements
  GreetingService {

  protected void doGet(HttpServletRequest req,
    HttpServletResponse resp)
    throws ServletException, IOException
  {

    DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
      Query query = new Query("YourKind");
      PreparedQuery pq = datastore.prepare(query);
      // Iterate the date
      for (Entity result : pq.asIterable()) {
      Transaction txn = datastore.beginTransaction();
      try {
        datastore.delete(result.getKey());
        txn.commit();
      } finally {
        if (txn.isActive()) {
          txn.rollback();
        }
      } 
    }

    }// doGet

}// Class