t = db.index_check5;
t.drop();

t.save({
    "name": "Player1",
    "scores": [{"level": 1, "score": 100}, {"level": 2, "score": 50}],
    "total": 150
});
t.save({
    "name": "Player2",
    "total": 90,
    "scores": [{"level": 1, "score": 90}, {"level": 2, "score": 0}]
});

assert.eq(2, t.find({"scores.level": 2, "scores.score": {$gt: 30}}).itcount(), "A");
t.ensureIndex({"scores.level": 1, "scores.score": 1});
assert.eq(2, t.find({"scores.level": 2, "scores.score": {$gt: 30}}).itcount(), "B");