MongoDB GeoNear Aggregation Result Size Limits - mongodb

Question

I'm using MongoDB 2.6.3 to query against a large collection of geospatial data. Specifically, I'm looking at querying the dataset for all pings within a few kilometers of a central location, and then collapsing them by user identifier to get a count of how many pings each user has.
Naturally, I'm using MongoDB aggregation for this, and specifically the $geoNear pipeline stage. However, it looks like, even though aggregation returns a cursor in 2.6.0, the $geoNear still has restrictions on the size of the result set tied to when aggregation returned a document. Namely, aggregation with $geoNear is returning only 65,000 records, while an equivalent (cursored) query is returning 200,000+.
Does anyone have any insight as to how I can perform large-scale aggregation then with geoNear?
edit:
Sample document:
{
"initial_epoch_time" : 1370062800,
"location" : [
-72.3458073902,
41.8241332683
],
"_id" : ObjectId("540a34050dc2520000912286"),
"__v" : 0
}
The following cursored query returns a count of ~200,000 documents, which I suspect is the correct number:
var cursor = db.pings.find( { location : { $near: { $geometry: { type: 'Point', coordinates: [-71.10560939999999, 42.3465666] }, $maxDistance: 10*1000 } } } )
var ctr = 0;
while(cursor.hasNext())
{ ctr++;
var ping = cursor.next()
}
print(ctr)
while the following aggregation-based query:
var cursor = db.pings.aggregate ( [ {$geoNear: { near: {type: "Point", coordinates: [-71.10560939999999, 42.3465666]},limit: 100000000, spherical: true, maxDistance: 10*1000, distanceField: "distance"} } ] )
var ctr = 0;
while(cursor.hasNext())
{ ctr++;
var ping = cursor.next()
}
print(ctr)
returns ~65,000 documents, regardless of maxDistance.

Answer 1

$geoNear as an command has a 16MB document limit to the output. I've found out that you won't retrieve any errors but the document will be automatically cut to the aggregation's document size limit. You can test by reducing size of your documents in the collection. You will get more results when you make your collection's documents smaller.
Line 235:
https://github.com/mongodb/mongo/blob/master/src/mongo/db/commands/geo_near_cmd.cpp