MongoDB Java driver 3.x: How to pass allowDiskUse=true to aggregate() method?

Question

I\'m using mongo-java-driver 3.0.2.

I have a method that uses MongoCollection.aggregate(List pipeline) to sort and limit:

Answer 1

This still works on the 3.0.3 driver:

    MongoClient client = new MongoClient(new ServerAddress("127.0.0.1", 27017));

    DB test = client.getDB("test");

    DBCollection sample = test.getCollection("sample");

    List aggregationQuery = Arrays.asList(
            new BasicDBObject("$sort",new BasicDBObject("score",-1)),
            new BasicDBObject("$limit",1)
    );

    System.out.println(aggregationQuery);

    Cursor aggregateOutput = sample.aggregate(
            aggregationQuery,
            AggregationOptions.builder()
                    .allowDiskUse(true)
                    .build()
    );

    while ( aggregateOutput.hasNext() ) {
        DBObject doc = aggregateOutput.next();
        System.out.println(doc);
    }

Of course you can also use newer classes as well:

    MongoClient client = new MongoClient(new ServerAddress("192.168.2.4", 27017));

    MongoDatabase db = client.getDatabase("test");

    MongoCollection collection = db.getCollection("sample");

    AggregateIterable result = collection.aggregate(Arrays.asList(
            new BasicDBObject("$sort", new BasicDBObject("score", -1)),
            new BasicDBObject("$limit", 1)
    )).allowDiskUse(true);

    MongoCursor cursor = result.iterator();

    while (cursor.hasNext()) {
        Document doc = cursor.next();
        System.out.println(doc);
    }

So .aggregate() on MongoCollection returns an AggregateIterable class instance, which has an .allowDiskuse() method as well as others to set aggregation options.