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Type:
Improvement
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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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Labels:None
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Minor Change
Observed behavior: Undefined and null are considered less than other values and as a result the computed $min value of a field will be null or undefined if null or undefined values are present for that field.
Expected behavior: We should specify some rules for operators to handle null and undefined. Perhaps null and undefined values should be excluded when calculating the min value.
Test:
> c.drop() true > c.save( { a:1 } ) > c.save( { a:null } ) > c.aggregate( { $group:{ _id:0, max:{ $max:'$a' }, min:{ $min:'$a' } } } ) { "result" : [ { "_id" : 0, "max" : 1, "min" : null // min is computed as null, not 1 } ], "ok" : 1 } > c.drop() true > c.save( { a:1 } ) > c.save( {} ) > c.aggregate( { $group:{ _id:0, max:{ $max:'$a' }, min:{ $min:'$a' } } } ) { "result" : [ { "_id" : 0, "max" : 1 } ], "ok" : 1 } // min is 'undefined' so excluded from the result
- is related to
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- Closed
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- related to
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DOCS-974 Document new aggregation $min behavior in 2.4 of skipping null and undefined values
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- Closed
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