Details
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Improvement
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Resolution: Won't Do
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Trivial - P5
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None
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None
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Query
Description
If $last operator is used in _id field for $group operation, for example:
db.test.aggregate([
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{ $sort : { score : 1 }},
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{ $group : {
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_id : { name : "$name",
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highest : { $last : "$score" }}}
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}
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])
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the following error message is displayed:
{
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"errmsg" : "exception: invalid operator '$last'",
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"code" : 15999,
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"ok" : 0
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}
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The error message is not so helpful for the user to fix the issue. It would help if we had a more specific error message, i.e. not to use $last in the _id field.
Similarly for $first operator.
BTW, the correct usage should be:
db.test.aggregate([
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{ $sort : { score : 1 }},
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{ $group : {
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_id : { name : "$name" },
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highest : { $last : "$score" }}
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}
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])
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Attachments
Issue Links
- related to
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SERVER-9577 new deverloper question on usage of Aggregation Framework
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- Closed
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