mongos> db.current_views.find({ ts:

{ $gte: 1352300700, $lt: 1352301000 }

, site: "506f0fea7cbdc70464aea9e9" } ).explain()
{
"clusteredType" : "ParallelSort",
"shards" : {
"vizvid-mongo-1:27019" : [
{
"cursor" : "BtreeCursor site_1",
"isMultiKey" : false,
"n" : 3413,
"nscannedObjects" : 4470768,
"nscanned" : 4470768,
"nscannedObjectsAllPlans" : 4470768,
"nscannedAllPlans" : 4470768,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 29754,
"nChunkSkips" : 0,
"millis" : 16086,
"indexBounds" :

{ "site" : [ [ "506f0fea7cbdc70464aea9e9", "506f0fea7cbdc70464aea9e9" ] ] }

,
"server" : "vizvid-mongo-1:27019"
}
]
},
"cursor" : "BtreeCursor site_1",
"n" : 3413,
"nChunkSkips" : 0,
"nYields" : 29754,
"nscanned" : 4470768,
"nscannedAllPlans" : 4470768,
"nscannedObjects" : 4470768,
"nscannedObjectsAllPlans" : 4470768,
"millisShardTotal" : 16086,
"millisShardAvg" : 16086,
"millis" : 16086,
"indexBounds" :

{ "site" : [ [ "506f0fea7cbdc70464aea9e9", "506f0fea7cbdc70464aea9e9" ] ] }

,
"server" : "vizvid-mongo-1:27019"
}
]
},
"cursor" : "BtreeCursor site_1",
"n" : 3413,
"nChunkSkips" : 0,
"nYields" : 29754,
"nscanned" : 4470768,
"nscannedAllPlans" : 4470768,
"nscannedObjects" : 4470768,
"nscannedObjectsAllPlans" : 4470768,
"millisShardTotal" : 16086,
"millisShardAvg" : 16086,
"numQueries" : 1,
"numShards" : 1,
"indexBounds" :

{ "site" : [ [ "506f0fea7cbdc70464aea9e9", "506f0fea7cbdc70464aea9e9" ] ] }

,
"millis" : 16087
}
###########################
.... Now with the hint ....
###########################
mongos> db.current_views.find({ ts:

{ $gte: 1352300700, $lt: 1352301000 }

, site: "506f0fea7cbdc70464aea9e9" } ).hint(

{ts:1, site:1}

).explain()
{
"clusteredType" : "ParallelSort",
"shards" : {
"vizvid-mongo-1:27019" : [
{
"cursor" : "BtreeCursor ts_1_site_1",
"isMultiKey" : false,
"n" : 3413,
"nscannedObjects" : 3413,
"nscanned" : 3472,
"nscannedObjectsAllPlans" : 3413,
"nscannedAllPlans" : 3472,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 1,
"nChunkSkips" : 0,
"millis" : 27,
"indexBounds" :

{ "ts" : [ [ 1352300700, 1352301000 ] ], "site" : [ [ "506f0fea7cbdc70464aea9e9", "506f0fea7cbdc70464aea9e9" ] ] }

,
"server" : "vizvid-mongo-1:27019"
}
]
},
"cursor" : "BtreeCursor ts_1_site_1",
"n" : 3413,
"nChunkSkips" : 0,
"nYields" : 1,
"nscanned" : 3472,
"nscannedAllPlans" : 3472,
"nscannedObjects" : 3413,
"nscannedObjectsAllPlans" : 3413,
"millisShardTotal" : 27,
"millisShardAvg" : 27,
"numQueries" : 1,
"numShards" : 1,
"indexBounds" :

{ "ts" : [ [ 1352300700, 1352301000 ] ], "site" : [ [ "506f0fea7cbdc70464aea9e9", "506f0fea7cbdc70464aea9e9" ] ] }

,
"millis" : 29
}