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Type: New Feature
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Resolution: Done
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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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Fully Compatible
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Query 16 (06/24/16)
Syntax
{ $sortByCount: <arbitrary non-object expression, see 'Behavior' for why> }
Examples
> db.example.insert([ {_id: 0, x: 1}, {_id: 1, x: 2}, {_id: 2, x: 1}, {_id: 3, x: 0} ]); > db.example.aggregate([{$sortByCount: "$x"}]) {_id: 1, count: 2} {_id: 0, count: 1} {_id: 2, count: 1} // Example #2 > db.example.drop(); > db.example.insert([ {_id: 0, x: 1.4}, {_id: 1, x: 2.3}, {_id: 2, x: 1.1}, {_id: 3, x: 0.5} ]); // Note this is an expression, so does not count as an "object" for the sake of erroring. > db.example.aggregate([{$sortByCount: {$floor: "$x"}}]) {_id: 1, count: 2} {_id: 0, count: 1} {_id: 2, count: 1} // Example #3 > db.example.aggregate([{$sortByCount: {field1: "$x", field2: "$y"}}]) Error!
Behavior
- This stage is syntactic sugar for the following:
{ $group: { _id: <expression>, count: {$sum: 1} } }, {$sort: {count: -1}}
- We restrict the expression to not be an object so that we might be able to add further arguments to $sortByCount in the future.
- is depended on by
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CSHARP-1693 Add $sortByCount aggregation stage
- Closed
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JAVA-2232 Add builder for $sortByCount aggregation stage
- Closed
- is related to
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SERVER-1635 Faceting support
- Closed
- related to
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DRIVERS-297 Aggregation Framework Support for 3.4
- Closed