Details
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Improvement
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Status: Closed
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Major - P3
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Resolution: Fixed
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None
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Minor Change
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v4.7, v4.4
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Query 2020-06-29, Query 2020-07-13, Query 2020-07-27
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(copied to CRM)
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16
Description
If there is an extra $sort that's identical to one before it, and there's a $limit after it, it causes an unfortunate full $sort of every document before the second sort which absorbed $limit is executed.
db.c.explain().aggregate([ {$sort: {a: 1}},{$sort:{a:1}},{$limit:5}]);
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{
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"stages" : [
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{
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"$cursor" : {
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"query" : {
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|
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},
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"sort" : {
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"a" : 1
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},
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"queryPlanner" : {
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"plannerVersion" : 1,
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"namespace" : "test.c",
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"indexFilterSet" : false,
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"parsedQuery" : {
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},
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"winningPlan" : {
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"stage" : "EOF"
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},
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"rejectedPlans" : [ ]
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}
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}
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},
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{
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"$sort" : {
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"sortKey" : {
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"a" : 1
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},
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"limit" : NumberLong(5)
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}
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}
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],
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"ok" : 1
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}
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Attachments
Issue Links
- causes
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SERVER-50897 Fix Sort/Limit/Sort Optimization
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- Closed
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