Details
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Improvement
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Resolution: Unresolved
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Major - P3
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None
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None
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Query Optimization
Description
As you can see below - it just happens to return an empty object, but proceeds without error. It seems better to either (a) error or (b) return an array. We don't have a 'set' data type in the BSON spec, so I don't see how we could get it to work and round trip seamlessly, but this experience isn't great.
> db.foo.aggregate([{
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$project: {
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js_res: {
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$function: { |
lang: "js", |
body: function() { |
return new Set([1, 2]); |
},
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args: []
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}
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}
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}
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}])
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{ "_id" : ObjectId("5f3c24f10efd1cb7f0a88f4a"), "js_res" : { } } |
{ "_id" : ObjectId("5f3c24f60efd1cb7f0a88f4b"), "js_res" : { } } |
{ "_id" : ObjectId("5f47f9411945d1527c6b0368"), "js_res" : { } } |
{ "_id" : ObjectId("5f47f9c71945d1527c6b0369"), "js_res" : { } } |
{ "_id" : ObjectId("5f47fa721945d1527c6b036a"), "js_res" : { } } |
As a workaround, you can use the [...set] syntax to expand the set into an array:
> db.foo.aggregate([{
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$project: {
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js_res: {
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$function: { |
lang: "js", |
body: function() { |
return [...new Set([1, 2])]; |
},
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args: []
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}
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}
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}
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}])
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{ "_id" : ObjectId("5f3c24f10efd1cb7f0a88f4a"), "js_res" : [ 1, 2 ] } |
{ "_id" : ObjectId("5f3c24f60efd1cb7f0a88f4b"), "js_res" : [ 1, 2 ] } |
{ "_id" : ObjectId("5f47f9411945d1527c6b0368"), "js_res" : [ 1, 2 ] } |
{ "_id" : ObjectId("5f47f9c71945d1527c6b0369"), "js_res" : [ 1, 2 ] } |
{ "_id" : ObjectId("5f47fa721945d1527c6b036a"), "js_res" : [ 1, 2 ] } |
Attachments
Issue Links
- is related to
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SERVER-34281 ES6 arrow functions (lambdas) do not work with map-reduce
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- Closed
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- Backlog
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- Closed
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- Closed
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- related to
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- Closed
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