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Type:
Bug
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Resolution: Duplicate
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Priority:
Trivial - P5
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None
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Affects Version/s: 2.4.5
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Component/s: None
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None
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ALL
The indexOnly in an explain() is set to true even if the query needs fields which aren't in the index.
This is the example collection:
db.test.insert([{a:1,c:1},{a:2,c:1}])
db.test.ensureIndex({c:1})
db.test.find({a:1,c:1},{_id:0,c:1}).explain()
This is what the explain looks like:
> db.test.find({a:1,c:1},{_id:0,c:1}).explain()
{
"cursor" : "BtreeCursor c_1",
"isMultiKey" : false,
"n" : 1,
"nscannedObjects" : 2,
"nscanned" : 2,
"nscannedObjectsAllPlans" : 4,
"nscannedAllPlans" : 4,
"scanAndOrder" : false,
"indexOnly" : true,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 0,
"indexBounds" : {
"c" : [
[
1,
1
]
]
},
"server" : "server:27017"
}
indexOnly is set to true but MongoDB has to query on field a which is not part of the index c_1 - so it has to be false.
- duplicates
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- Closed
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