Details
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Bug
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Status: Closed
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Major - P3
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Resolution: Duplicate
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2.4.3, 2.4.7
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None
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ALL
Description
Setting the .min() or .max() explicitly on a find and using a descending sort seems not to work.
> db.docs.drop()
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> for (var i=0; i<10; i++) { db.docs.insert({number: i}) }
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> db.docs.ensureIndex({number: 1})
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no sort
> db.docs.find().max({number: 4})
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e3"), "number" : 0 }
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e4"), "number" : 1 }
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e5"), "number" : 2 }
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e6"), "number" : 3 }
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ascending sort
> db.docs.find().max({number: 4}).sort({number: 1})
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e3"), "number" : 0 }
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e4"), "number" : 1 }
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e5"), "number" : 2 }
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{ "_id" : ObjectId("51834d678d284e5c5e3ea7e6"), "number" : 3 }
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descending sort
> db.docs.find().max({number: 4}).sort({number: -1})
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>
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I would expect to get the 4 documents back in the 'reverse order' case, in number order: 3, 2, 1, 0. Instead, I get 0 documents back.
explain of ascending sort
> db.docs.find().max({number: 4}).sort({number: 1}).explain()
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{
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"cursor" : "BtreeCursor number_1",
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"isMultiKey" : false,
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"n" : 4,
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"nscannedObjects" : 4,
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"nscanned" : 4,
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"nscannedObjectsAllPlans" : 4,
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"nscannedAllPlans" : 4,
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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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"start" : {
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"number" : {
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"$minElement" : 1
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}
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},
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"end" : {
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"number" : 4
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}
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},
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"server" : "capslock.local:27017"
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}
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explain of descending sort
> db.docs.find().max({number: 4}).sort({number: -1}).explain()
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{
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"cursor" : "BtreeCursor number_1 reverse",
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"isMultiKey" : false,
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"n" : 0,
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"nscannedObjects" : 0,
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"nscanned" : 0,
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"nscannedObjectsAllPlans" : 0,
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"nscannedAllPlans" : 0,
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"scanAndOrder" : false,
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"indexOnly" : false,
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"nYields" : 0,
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"nChunkSkips" : 0,
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"millis" : 0,
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"indexBounds" : {
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"start" : {
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"number" : {
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"$minElement" : 1
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}
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},
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"end" : {
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"number" : 4
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}
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},
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"server" : "capslock.local:27017"
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}
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Attachments
Issue Links
- depends on
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- Closed
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SERVER-10026 New query system
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- Closed
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- duplicates
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- Closed
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- is duplicated by
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SERVER-9540 How to get the previous mongoDB document from a compound index
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- Closed
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- is related to
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SERVER-17076 Consider removing IndexBounds::isSimpleRange
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- Closed
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- related to
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- Closed
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