> db.test.createIndex({loc:'2d'});
> db.test.insert({_id: 1, loc:[0, 0]});
> // point [1, 0] is farther than 0 units from origin as expected
> printjson(db.test.findOne({
...     loc:{
...         $near:[1, 0],
...         $maxDistance: 0}}));
null
> // but GeoJSON point [1, 0] is 0 units from origin??
> printjson(db.test.findOne({
...     loc:{
...         $near:{
...             $geometry:{
...                 type:'Point',
...                 coordinates:[1, 0]}},
...         $maxDistance: 0}}));
{ "_id" : 1, "loc" : [ 0, 0 ] }
> // Wrong sort order:
> db.test.insert({_id: 2, loc:[1, 0]});
> db.test.find({
...     loc:{
...         $near:{
...             $geometry:{
...                 type:'Point',
...                 coordinates:[2, 0]}}}});
{ "_id" : 1, "loc" : [  0,  0 ] }
{ "_id" : 2, "loc" : [  1,  0 ] }
> // GeoJSON point [2, 0] is 1 unit from [1, 0], but 0 units from origin?
> db.test.find({
...     loc:{
...         $near:{
...             $geometry:{
...                 type:'Point',
...                 coordinates:[2, 0]}},
...         $maxDistance: 1}});
{ "_id" : 1, "loc" : [  0,  0 ] }
{ "_id" : 2, "loc" : [  1,  0 ] }
>
> db.test.find({
...     loc:{
...         $near:{
...             $geometry:{
...                 type:'Point',
...                 coordinates:[2, 0]}},
...         $maxDistance:.999}});
{ "_id" : 1, "loc" : [  0,  0 ] }