I have a query: {"$query"=>{"user_id"=>"512f7960534dcda22b000491", "$or"=>[{"when_tz"=>{"$gte"=>2010-06-24 04:00:00 UTC, "$lt"=>2010-06-25 04:00:00 UTC}}, {"when_tz"=>{"$gte"=>2011-06-24 04:00:00 UTC, "$lt"=>2011-06-25 04:00:00 UTC}}, {"when_tz"=>{"$gte"=>2012-06-24 04:00:00 UTC, "$lt"=>2012-06-25 04:00:00 UTC}}], "_type"=>{"$in"=>["FacebookImageItem", "FoursquareImageItem", "InstagramItem", "TwitterImageItem", "Image"]}}, "$explain"=>true, "$orderby"=>{"when_tz"=>1}} And an index: { user_id: 1, _type: 1, when_tz: 1 } Explain: {"cursor"="BtreeCursor user_id_1__type_1_facebook_id_1 multi", "isMultiKey"=false, "n"=28, "nscannedObjects"=15094, "nscanned"=15098, "nscannedObjectsAllPlans"=181246, "nscannedAllPlans"=241553, "scanAndOrder"=true, "indexOnly"=false, "nYields"=12, "nChunkSkips"=0, "millis"=2869, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "facebook_id"=[[{"$minElement"=1}, {"$maxElement"=1}]]}, "allPlans"=[{"cursor"="BtreeCursor user_id_1__type_1_facebook_id_1 multi", "n"=28, "nscannedObjects"=15094, "nscanned"=15098, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "facebook_id"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1__type_1_twitter_id_1 multi", "n"=28, "nscannedObjects"=15094, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "twitter_id"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1__type_1_instagram_id_1 multi", "n"=28, "nscannedObjects"=15094, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "instagram_id"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1__type_1_foursquare_id_1 multi", "n"=28, "nscannedObjects"=15094, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "foursquare_id"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_phash_1", "n"=21, "nscannedObjects"=15097, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "phash"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_aperature_1_shutter_speed_1_when_tz_1", "n"=25, "nscannedObjects"=35, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "aperature"=[[{"$minElement"=1}, {"$maxElement"=1}]], "shutter_speed"=[[{"$minElement"=1}, {"$maxElement"=1}]], "when_tz"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_image_hash_1", "n"=22, "nscannedObjects"=15097, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "image_hash"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_time_zone_guessed_1_when_tz_-1", "n"=23, "nscannedObjects"=32, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "time_zone_guessed"=[[{"$minElement"=1}, {"$maxElement"=1}]], "when_tz"=[[{"$maxElement"=1}, {"$minElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_time_zone_guessed_1_when_tz_1", "n"=24, "nscannedObjects"=33, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "time_zone_guessed"=[[{"$minElement"=1}, {"$maxElement"=1}]], "when_tz"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_time_zone_guessed_1_when_utc_-1", "n"=23, "nscannedObjects"=15097, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "time_zone_guessed"=[[{"$minElement"=1}, {"$maxElement"=1}]], "when_utc"=[[{"$maxElement"=1}, {"$minElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_time_zone_guessed_1_when_utc_1", "n"=24, "nscannedObjects"=15097, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "time_zone_guessed"=[[{"$minElement"=1}, {"$maxElement"=1}]], "when_utc"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1_original_shared_item_id_1", "n"=24, "nscannedObjects"=15097, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "original_shared_item_id"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1__type_1_s3_tmp_file_1 multi", "n"=28, "nscannedObjects"=15094, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "s3_tmp_file"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1__type_1_processed_-1_uploaded_-1_image_device_1 multi", "n"=28, "nscannedObjects"=15094, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "processed"=[[{"$maxElement"=1}, {"$minElement"=1}]], "uploaded"=[[{"$maxElement"=1}, {"$minElement"=1}]], "image_device"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BtreeCursor user_id_1__type_1_when_tz_1 multi", "n"=28, "nscannedObjects"=28, "nscanned"=15097, "indexBounds"={"user_id"=[["512f7960534dcda22b000491", "512f7960534dcda22b000491"]], "_type"=[["FacebookImageItem", "FacebookImageItem"], ["FoursquareImageItem", "FoursquareImageItem"], ["Image", "Image"], ["InstagramItem", "InstagramItem"], ["TwitterImageItem", "TwitterImageItem"]], "when_tz"=[[{"$minElement"=1}, {"$maxElement"=1}]]}}, {"cursor"="BasicCursor", "n"=0, "nscannedObjects"=15097, "nscanned"=15097, "indexBounds"={}}], "server"=""} Any idea how to get it to hit the indexes?