[SERVER-84549] Do not count fetch as read in SBE trial run Created: 04/Jan/24  Updated: 09/Jan/24  Resolved: 09/Jan/24

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

Type: Task Priority: Major - P3
Reporter: Ivan Fefer Assignee: Ivan Fefer
Resolution: Won't Fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Sprint: QE 2024-01-22
Participants:

 Description   

SBE multi planner currently counts every read: index seek/scan and collection seek/scan as a "read" and the main measure of SBE plan in multi planner is reads per doc.

Because of this, plan with fetch needs to be twice as efficient as plan without fetch to be selected. In classic, noFetch bonus is much smaller.

To make reads more comparable with classic's works and avoid this problem, we should not count fetch stage in trial run tracker.



 Comments   
Comment by Ivan Fefer [ 09/Jan/24 ]

Fetch is an expensive operation and having multi planner count it as a separate read is preferable.

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