# Original, (working) collection.group command.
#
db.myCollection.group({'key': {'ip1':true},
                          'reduce': function(obj,prev) { prev.count += 1; },
                          'initial': { 'count':1 }
})


# Roughly Equivalent Aggregation query (NOT working)
#
> db.runCommand({
...     'aggregate': "myCollection",
...     'pipeline': [
...         {'$group': {
...             '_id': '$ip1',
...             'count': {'$sum':1}
...         }}
...     ]
... })
{
	"errmsg" : "exception: can't compare values of BSON types 16 and 18",
	"code" : 16016,
	"ok" : 0
}
>