I had an existing index:

{l:1, group:1}

I've been doing queries like:

{ t: "<a href="/graphics-cards/asus-eah5670-di-512md5/">Asus EAH5670/DI/512M...", tLcHash: 8661900111881084748, l: "eng", g:

{ $ref: "Group", $id: ObjectId('4defe4897112ede06261f73a') }

}

so I added a new index in the foreground:

{tLcHash:1, l:1, group:1}

but immediately after, an explain shows:

{
"cursor" : "BtreeCursor l_1_group_1",
"nscanned" : 0,
"nscannedObjects" : 0,
"n" : 0,
"millis" : 2,
"nYields" : 0,
"nChunkSkips" : 0,
"isMultiKey" : false,
"indexOnly" : false,
"indexBounds" : {
"l" : [
[
"eng",
"eng"
]
],
"group" : [
[

{ "$minElement" : 1 }

,

{ "$maxElement" : 1 }

]
]
}
}

Are the query stats not getting reset?