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Type:
Question
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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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None
Observed behavior: The result of multiplying two 32 bit integers is a 32 bit integer, even if there is an overflow.
Proposed behavior: Rather than overflow, an alternative numeric type will be used to store the result when possible.
c = db.c;
c.drop();
c.save( {} );
assert.eq( NumberLong( '4611686018427390000' ),
// Current behavior on overflow is for the multiplication result to be zero.
c.aggregate( { $project:{ a:{ $multiply:[ NumberInt( '2147483648' ), NumberInt( '2147483648' )\
] } } } ).result[ 0 ].a );
Consider addition and subtraction overflow as well. For numeric addition and subtraction, adding two 32 bit ints will produce a 32 bit int. Currently division is implemented to always return a double.
Also consider for accumulators like $sum.
- is duplicated by
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SERVER-6510 $sum can cause int overflow
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- Closed
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- is related to
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SERVER-5239 $project should have numeric type coercion operators
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- Closed
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- related to
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SERVER-6203 Aggregation operators should have well defined implicit type coercion behavior.
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- Backlog
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- Closed
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