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Type:
Bug
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Resolution: Duplicate
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Priority:
Major - P3
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None
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Affects Version/s: 2.5.2
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Component/s: Aggregation Framework
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None
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ALL
In the following example, I'm attempting to compute the product of all x fields in a collection. After the $group step, vals would be an array of these values. I would expect to be able to pass vals directly to $multiply and have it compute the product; however, $multiply instead considers the de-referenced value as an argument to be multiplied instead of the argument array.
I imagine this is related to $multiply supporting a scalar argument, in which case it returns that numeric value * 1 (and complains if the value is not numeric).
> db.foo.find()
{ "_id" : ObjectId("522784a423582cd7f71acca7"), "x" : 2 }
{ "_id" : ObjectId("522784a523582cd7f71acca8"), "x" : 3 }
{ "_id" : ObjectId("522784a623582cd7f71acca9"), "x" : 4 }
> pipeline
[
{
"$group" : {
"_id" : 1,
"vals" : {
"$push" : "$x"
}
}
},
{
"$project" : {
"product" : {
"$multiply" : "$vals"
}
}
}
]
> db.foo.aggregate(pipeline)
Error: Printing Stack Trace
at printStackTrace (src/mongo/shell/utils.js:37:15)
at DBCollection.aggregate (src/mongo/shell/collection.js:897:9)
at (shell):1:8
Wed Sep 4 15:07:05.712 JavaScript execution failed: aggregate failed: {
"errmsg" : "exception: $multiply only supports numeric types, not Array",
"code" : 16555,
"ok" : 0
} at src/mongo/shell/collection.js:L898
Here's an example of an array value being passed as an argument to be multiplied (using all literals):
> db.foo.aggregate({$project:{p:{$multiply:[[3]]}}})
Error: Printing Stack Trace
at printStackTrace (src/mongo/shell/utils.js:37:15)
at DBCollection.aggregate (src/mongo/shell/collection.js:897:9)
at (shell):1:8
Wed Sep 4 15:12:32.572 JavaScript execution failed: aggregate failed: {
"errmsg" : "exception: $multiply only supports numeric types, not Array",
"code" : 16555,
"ok" : 0
} at src/mongo/shell/collection.js:L898
- duplicates
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SERVER-10676 $multiply does not support a reference to an array
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- Closed
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- is related to
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- Backlog
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- related to
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SERVER-31991 Allow n-ary aggregation expressions to compute their array of arguments dynamically
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- Backlog
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