[SERVER-79635] [CQF] Consider the number of projections produced by a PhysicalScan when determining its cost Created: 02/Aug/23  Updated: 10/Aug/23  Resolved: 10/Aug/23

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

Type: Improvement Priority: Major - P3
Reporter: Ben Shteinfeld Assignee: Backlog - Query Optimization
Resolution: Duplicate Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Duplicate
duplicates SERVER-76272 Improve cost model for Filter and Eva... Backlog
Related
related to SERVER-79633 [CQF] Consider the expression child o... Backlog
Assigned Teams:
Query Optimization
Participants:

 Description   

Currently the cost of a PhysicalScan node (and Seek and IndexScan) is a function of its cardinality estimate and startup/marginal cost coefficients. It ignores the number of projections it must produce. This leads to plans that incorrectly have identical costs according to the cost model, but in reality have different runtimes.


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