-
Type:
Improvement
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Resolution: Fixed
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: Aggregation Framework
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Minor Change
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v4.7, v4.4
-
Query 2020-06-29, Query 2020-07-13, Query 2020-07-27
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(copied to CRM)
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16
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}]);
{
"stages" : [
{
"$cursor" : {
"query" : {
},
"sort" : {
"a" : 1
},
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "test.c",
"indexFilterSet" : false,
"parsedQuery" : {
},
"winningPlan" : {
"stage" : "EOF"
},
"rejectedPlans" : [ ]
}
}
},
{
"$sort" : {
"sortKey" : {
"a" : 1
},
"limit" : NumberLong(5)
}
}
],
"ok" : 1
}
- causes
-
SERVER-50897 Fix Sort/Limit/Sort Optimization
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- Closed
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