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  1. Core Server
  2. SERVER-67160

Do not display distribution-related properties if optimizing without intra-query parallelism

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Details

    • Improvement
    • Status: Open
    • Major - P3
    • Resolution: Unresolved
    • None
    • None
    • None
    • None
    • QO 2022-06-27, QO 2022-07-11, QO 2022-07-25, QO 2022-08-08, QO 2022-08-22, QO 2022-09-05, QO 2022-09-19, QO 2022-10-03

    Description

      Specifically for BSON explain (not for V1 and V2):

      • If optimizing under DOP = 1
      • Do not add the DistributionRequirement and DistributionAvailability properties to the explain.
      • Those default to Centralized in such cases, and are meaningful only for cases where DOP > 1.

       

      For example consider the following printout which displays Centralized distribution.

       

      [j0] ********* Optimized ABT *********
      [j0] Properties [cost: 2e-06, localCost: 0, adjustedCE: 0]
      [j0] |   |   Logical:
      [j0] |   |       cardinalityEstimate:
      [j0] |   |           ce: 0
      [j0] |   |       projections:
      [j0] |   |           scan_0
      [j0] |   |       collectionAvailability:
      [j0] |   |       distributionAvailability:
      [j0] |   |           distribution:
      [j0] |   |               type: Centralized
      [j0] |   Physical:
      [j0] |       distribution:
      [j0] |           type: Centralized
      [j0] Root []
      [j0] |   |   projections:
      [j0] |   |       scan_0
      [j0] |   RefBlock:
      [j0] |       Variable [scan_0]
      [j0] Properties [cost: 2e-06, localCost: 2e-06, adjustedCE: 0]
      [j0] |   |   Logical:
      [j0] |   |       cardinalityEstimate:
      [j0] |   |           ce: 0
      [j0] |   |       projections:
      [j0] |   |           scan_0
      [j0] |   |       collectionAvailability:
      [j0] |   |       distributionAvailability:
      [j0] |   |           distribution:
      [j0] |   |               type: Centralized
      [j0] |   Physical:
      [j0] |       projections:
      [j0] |           scan_0
      [j0] |       distribution:
      [j0] |           type: Centralized
      [j0] Evaluation []
      [j0] |   BindBlock:
      [j0] |       [scan_0]
      [j0] |           Const [Nothing]
      [j0] LimitSkip []
      [j0] |   limitSkip:
      [j0] |       limit: 0
      [j0] |       skip: 0
      [j0] CoScan []
      [j0] ********* Optimized ABT *********
      

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            james.wahlin@mongodb.com James Wahlin
            svilen.mihaylov@mongodb.com Svilen Mihaylov
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              Created:
              Updated: