Details
Description
When using $all with $elemMatch criteria, the query uses wider bounds than what it should have used (v2.4 behaves correctly in selecting narrow bounds). Following are steps indicates the wider bounds being queried on the array field "bc":
db.x.drop();
|
db.x.ensureIndex({a: 1, "dims.b": 1, "dims.c": 1}); |
db.x.insert({a: 1, bc: [{b: "abc", c: "xyz"}, {b: "gsh", c: "ysh"]}); |
db.x.find({
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        "a" : 1, |
        "bc" : { |
                "$all" : [ |
                        {
|
                                "$elemMatch" : { |
                                        "b" : "pl", |
                                        "c" : "tgit" |
                                }
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                        },
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                        {
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                                "$elemMatch" : { |
                                        "b" : "xy", |
                                        "c" : "ak" |
                                        }
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                         }
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                ]
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        }
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}).explain();
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Explain with $all:
{
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"cursor" : "BtreeCursor a_1_bc.b_1_bc.c_1",
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"isMultiKey" : true,
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"n" : 0,
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"nscannedObjects" : 2,
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"nscanned" : 3,
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"nscannedObjectsAllPlans" : 2,
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"nscannedAllPlans" : 3,
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"scanAndOrder" : false,
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"indexOnly" : false,
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"nYields" : 0,
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"nChunkSkips" : 0,
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"millis" : 0,
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"indexBounds" : {
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"a" : [
|
[
|
1,
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1
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]
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],
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"bc.b" : [
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[
|
{
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"$minElement" : 1
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},
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{
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"$maxElement" : 1
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}
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]
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],
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"bc.c" : [
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[
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{
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"$minElement" : 1
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},
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{
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"$maxElement" : 1
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}
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]
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]
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},
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"filterSet" : false
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}
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Attachments
Issue Links
- is duplicated by
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SERVER-17221 Query on key-val array using $all and $elemMatch does not seem to correctly use indexes
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- Closed
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- related to
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- Closed
-