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  1. Core Server
  2. SERVER-14872

Aggregation pipeline project expression operator to concatenate multiple arrays into one

          Details

          • Type: Improvement
          • Status: Closed
          • Priority: Major - P3
          • Resolution: Fixed
          • Affects Version/s: None
          • Fix Version/s: 3.1.5
          • Component/s: Aggregation Framework
          • Labels:
            None
          • Backwards Compatibility:
            Fully Compatible
          • Sprint:
            Quint Iteration 4, Quint Iteration 5

            Description

            I need to count the number of duplicate IDs that occur across all documents in a collection. However, this very simple aggregation is complicated by the fact that the IDs in question may appear in multiple fields in the input document.

            Suppose I have input documents like the one below:

            {
            		 
              a : [1, 2, 3],
            		 
              b : [2, 4, 5]
            		 
            }

            I'd like to transform this to a document that looks like:

            {
            		 
              c : [1, 2, 3, 2, 4, 5]
            		 
            }

            From this point, it is straightforward to unwind and group on c to get to the desired result.

            The above transformation is similar to what would be achieved using the $setUnion operator, but here I do not want to filter out duplicate values.

            Therefore, this request is for an operator similar to $setUnion but which does not filter out duplicate values.

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                Issue Links

                is duplicated by

                Improvement - An improvement or enhancement to an existing feature or task. SERVER-5919 Add set/array operations to $unwind in new aggregation framework

                • Minor - P4 - Minor loss of function, or other problem where easy workaround is present.
                • Closed
                is related to

                New Feature - A new feature of the product, which has yet to be developed. SERVER-17258 Add $reduce expression operator for rollup of arrays

                • Major - P3 - Major loss of function.
                • Closed
                related to

                New Feature - A new feature of the product, which has yet to be developed. CSHARP-1364 Aggregation pipeline project expression operator to concatenate multiple arrays into one

                • Major - P3 - Major loss of function.
                • Closed

                Task - A task that needs to be done. DRIVERS-234 Aggregation Builder Support for 3.2

                • Major - P3 - Major loss of function.
                • Closed

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                      Dates

                      • Created:
                        Updated:
                        Resolved: