> part.findOne()
{
	"_id" : ObjectId("54bf9b01bef23df039fb0caf"),
	"mac" : "0026C76A6E08",
	"location" : {
		"timestamp" : ISODate("2015-01-21T12:27:31Z"),
		"pos_status" : 0,
		"x" : 49.37150573730469,
		"y" : 5.593080043792725,
		"ip" : ""
	},
	"customer" : [ ],
	"ofi" : [
		{
			"oft" : 0,
			"id" : "0"
		},
		{
			"oft" : 0,
			"id" : "1"
		},
		{
			"oft" : 0,
			"id" : "A"
		}
	]
}

> part.ensureIndex({'location.timestamp': 1, 'ofi.id': 1})
{
	"createdCollectionAutomatically" : false,
	"numIndexesBefore" : 2,
	"numIndexesAfter" : 3,
	"ok" : 1
}

> part.find({'location.timestamp': {'$gte': new Date('2015-01-21 12:00:00'), '$lt': new Date('2015-01-21 22:00:00')}}).hint({'location.timestamp':1, 'ofi.id': 1}).explain()
{
	"cursor" : "BtreeCursor location.timestamp_1_ofi.id_1",
	"isMultiKey" : true,
	"n" : 500,
	"nscannedObjects" : 500,
	"nscanned" : 1500,
	"nscannedObjectsAllPlans" : 500,
	"nscannedAllPlans" : 1500,
	"scanAndOrder" : false,
	"indexOnly" : false,
	"nYields" : 11,
	"nChunkSkips" : 0,
	"millis" : 2,
	"indexBounds" : {
		"location.timestamp" : [
			[
				true,
				ISODate("2015-01-21T14:00:00Z")
			]
		],
		"ofi.id" : [
			[
				{
					"$minElement" : 1
				},
				{
					"$maxElement" : 1
				}
			]
		]
	},
	"server" : "smartac-2015:27017",
	"filterSet" : false
}