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Type:
Bug
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Resolution: Duplicate
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Priority:
Major - P3
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None
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Affects Version/s: 2.0.4
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Component/s: Querying
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Labels:None
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Environment:Window 7, single node
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ALL
I was working through the exercises in the training course in the indexing section. As a variation from the instructions, one of the students tried to explain() what should have been an index-only query, but it was not reported as such by explain. To recreate, load the twitter.tweets collection from the training sample data set. Then:
> db.tweets.find({'user.friends_count:{$gt:100},
'user.followers_count':{$gt:100}},
{'user.friends_count':1, _id:0}).explain();
{
"cursor" : "BtreeCursor user.friends_count_1_user.followers_count_1",
"nscanned" : 26377,
"nscannedObjects" : 25984,
"n" : 25984,
"millis" : 458,
"nYields" : 0,
"nChunkSkips" : 0,
"isMultiKey" : false,
"indexOnly" : false,
"indexBounds" : {
"user.friends_count" : [
[
100,
1.7976931348623157e+308
]
],
"user.followers_count" : [
[
100,
1.7976931348623157e+308
]
]
}
}
>
Note the indexOnly field in the explain() result is false, even though the selection list only includes the first field of the index key.
- duplicates
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SERVER-2104 covered index should support dotted fields
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- Closed
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