[SERVER-71038] Investigate LLT mixed regressions Created: 02/Nov/22  Updated: 02/Feb/24

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

Type: Task Priority: Major - P3
Reporter: Mihai Andrei Assignee: Backlog - Query Execution
Resolution: Unresolved Votes: 0
Labels: pm2697-m3
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: File SBE_short_benchmark.svg     File SBE_without_hints.svg     File classic_short_benchmark.svg     File classic_without_hints.svg    
Issue Links:
Problem/Incident
Related
related to SERVER-72803 Cache hinted SBE queries Closed
Assigned Teams:
Query Execution
Backwards Compatibility: Fully Compatible
Sprint: QE 2023-05-15, QE 2023-05-29, QE 2023-06-12, QE 2023-06-26, QE 2023-07-10, QE 2023-07-24, QE 2023-08-07, QE 2023-08-21, QE 2023-09-04, QE 2023-09-18, QE 2023-10-02, QE 2023-10-16, QE 2023-10-30, QE 2023-11-13, QE 2023-11-27, QE 2023-12-11, QE 2023-12-25, QE 2024-01-08, QE 2024-01-22, QE 2024-02-05, QE 2024-02-19
Participants:
Linked BF Score: 35
Story Points: 10

 Description   
Long.Query.Baseline.findOne -30.18878612
Long.Query.Benchmark.findOne -22.61465156
llt_mixed Medium.Query.Baseline.findOne -24.30839036
llt_mixed Medium.Query.Benchmark.findOne -24.05129074
llt_mixed Short.Query.Baseline.findOne -19.7895922
llt_mixed Short.Query.Benchmark.findOne -26.9140599
 

Oddly enough I feel that this shouldn't be an issue because it's a findOne query, but it's not clear what the predicate is.



 Comments   
Comment by Ian Boros [ 04/Apr/23 ]

Summary: the regressions in the findOne queries appear to be the same cause as for many other short-running queries: A lot of time is spent constructing the plan (nearly half).

Per in person discussion last week, I'm moving this to the backlog since it's been bumped to the next project, and there's other ongoing work to make plan creation/cloning faster.

Comment by David Storch [ 02/Mar/23 ]

alberto.massari@mongodb.com mihai.andrei@mongodb.com are the llt_mixed workloads now no longer showing a regression in SBE after these changes? If there is still a regression, then we should keep this ticket open for now.

Also, note that the work that zixuan.zhuang@mongodb.com is doing in SERVER-72803 results in a significant improvement for some of the llt_mixed workloads. 

Comment by Githook User [ 02/Mar/23 ]

Author:

{'name': 'Alberto Massari', 'email': 'alberto.massari@mongodb.com', 'username': 'albymassari'}

Message: SERVER-71038 Improve performance of plan building in SBE
Branch: master
https://github.com/mongodb/mongo/commit/20e995074cf7420ced7e46636ec0a78e2fd0c19f

Comment by Kyle Suarez [ 06/Jan/23 ]

LGTM

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