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  1. Core Server
  2. SERVER-4507

aggregation: optimize $group to take advantage of sorted sequences

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Details

    • Improvement
    • Status: Backlog
    • Major - P3
    • Resolution: Unresolved
    • None
    • None
    • Aggregation Framework
    • Query Execution
    • Fully Compatible
    • Query 10 (02/22/16), Query 11 (03/14/16), Query 12 (04/04/16)

    Description

      If the input to a $group is sorted by the _id, then only one bucket needs to be maintained at a time. This will reduce memory requirements significantly.

      We can examine the _id and take advantage of this if we can force an index scan on the key, if there are no intervening pipeline operations that would affect the results.

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              backlog-query-execution Backlog - Query Execution
              dan@mongodb.com Daniel Pasette (Inactive)
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                Created:
                Updated: