Question

I’m following the docs on this site: http://code.google.com/intl/sv-SE/appengine/docs/java/datastore/jdo/queries.html

From there I learned how to make queries but I seems only to work with one parameter. Here’s how I’m doing it successfully:

javax.jdo.Query q1 = pm.newQuery(Player.class);

q1.setFilter("isOpen == true");

List<Player> players = (List<Player>) q1.execute();

That fetches me all the Player object with the boolean isOpen == true. I can do the same thing with a Long, that works too.

Here’s the problem: When combining two conditions like this:

javax.jdo.Query q1 = pm.newQuery(Player.class);

q1.setFilter("isOpen == true && lastPing > 100");

List<Player> players = (List<Player>) q1.execute();

The app crashes. Here’s the error I’m getting:

Uncaught exception from servlet
com.google.appengine.api.datastore.DatastoreNeedIndexException: no
matching index found. The suggested index for this query is:
datastore-index kind=”Player” ancestor=”false” source=”manual”
property name=”isOpen” direction=”asc” property name=”lastPing”
direction=”asc” datastore-index

So, does anyone know why this is happening? Any help is greatly appreciated.

Answer 1

You can’t do an inequality filter along with another filter unless you have an index on the column for which you’re doing the inequality comparison. Add this to your datastore-indexes.xml in your WEB-INF folder and deploy it (either a full deploy or appcfg update-indexes):

<datastore-index kind="Player" ancestor="false">
        <property name="isOpen" direction="asc"/>
        <property name="lastPing" direction="asc"/>
    </datastore-index>