[SERVER-67160] Do not display distribution-related properties if optimizing without intra-query parallelism Created: 09/Jun/22  Updated: 27/Oct/23  Resolved: 06/Feb/23

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Improvement Priority: Major - P3
Reporter: Svilen Mihaylov (Inactive) Assignee: Svilen Mihaylov (Inactive)
Resolution: Works as Designed Votes: 0
Labels: cascades-starter, explain
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Query Optimization
Sprint: 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, QE 2022-10-17
Participants:

 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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