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  1. Core Server
  2. SERVER-3758

push limit down into index scan for sort + limit queries

    Details

    • Type: Improvement
    • Status: Open
    • Priority: Major - P3
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: Backlog
    • Component/s: Querying
    • Labels:

      Description

      index {a:1,b:1}
      find( {a:{$gte:2,$lte:4}} ).sort( {b:1} ).limit(5)

      There is a missing optimization for the query above. The query engine could scan only the first 5 values of b for each value of a.

      See SERVER-3122 for initial description and SERVER-3310 for a related case.

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                • Created:
                  Updated: