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  1. Core Server
  2. SERVER-4437

aggregation: support windowing operation on pipelines

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    Details

    • Type: New Feature
    • Status: Open
    • Priority: Major - P3
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: Backlog
    • Component/s: Aggregation Framework
    • Labels:
      None
    • Backwards Compatibility:
      Fully Compatible

      Description

      postgres supports a windowing capability that allows for calculations within a window of visible data; this is for streaming data.

      It's easy to imagine supporting something like a $window pipeline operator, which specifies how many documents to include in the window. Within, aggregate expressions can reference documents within the window using some kind of indexing. This can be used to calculate things like moving averages, e.g., have a window of 5 items, and create a computed field that is (doc[0] + doc[-1] + doc[-2] + doc[-3] + doc[-4])/5, or something like that.

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                • Created:
                  Updated: