[SERVER-65319] Adjust statistics counters to the new default value of allowDiskUse Created: 07/Apr/22  Updated: 29/Oct/23  Resolved: 02/May/22

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 6.0.0-rc4, 6.1.0-rc0

Type: Question Priority: Major - P3
Reporter: Romans Kasperovics Assignee: Romans Kasperovics
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Depends
Related
related to DOCS-15184 [SERVER] Investigate changes in SERVE... Closed
related to SERVER-64184 Track usage of allowDiskUse:true in a... Closed
Backwards Compatibility: Fully Compatible
Backport Requested:
v6.0
Sprint: QE 2022-05-02
Participants:

 Description   

PM-2742 changes the default of the allowDiskUse per-query parameter and introduces allowDiskUseByDefault per-node parameter. In this context, we might need to adjust the statistics.

  • SERVER-64184 added tracking the explicit use of allowDiskUse:true per-query parameter
  • Do we want to continue tracking the explicit use of allowDiskUse:true pas PM-2742? (true will be the new default)
  • Do we want to track the usage with find command as well?
  • Do we want to track the explicit use allowDiskUse:false?
  • Do we want to track both explicit and implicit use?
  • Do we want to track changes of the allowDiskUseByDefault parameter?


 Comments   
Comment by Githook User [ 03/May/22 ]

Author:

{'name': 'Romans Kasperovics', 'email': 'romans.kasperovics@mongodb.com', 'username': 'romanskas'}

Message: SERVER-65319 Count explicit use of allowDiskUse:false
Branch: v6.0
https://github.com/mongodb/mongo/commit/5f60d59336d13ea6c51cd6d1775188ceb725a4dd

Comment by Githook User [ 02/May/22 ]

Author:

{'name': 'Romans Kasperovics', 'email': 'romans.kasperovics@mongodb.com', 'username': 'romanskas'}

Message: SERVER-65319 Count explicit use of allowDiskUse:false
Branch: master
https://github.com/mongodb/mongo/commit/34ea442dda453616265650377d8d68404195c46f

Comment by David Storch [ 27/Apr/22 ]

Actually, I'm not sure if we quite settled this. christopher.harris@mongodb.com should we be counting only those queries which explicitly pass allowDiskUse:false over the wire? Or should we count those queries plus the ones which do not specify allowDiskUse but inherit a value of allowDiskUse:false because the system is configured with allowDiskUseByDefault:false?

Originally I was imagining that we would count both the queries which explicitly prohibit disk use and those which disallow disk use by virtue of "inheritance". But on second thought we may prefer to only count explicit allowDiskUse:false. For one thing, this is likely simpler to implement. But more importantly, I imagine that we are interested in two separate questions:

  1. How many mongod nodes exist on Atlas which use allowDiskUseByDefault:false?
  2. How many queries are run on Atlas (and against how many distinct clusters/projects) which explicitly pass allowDiskUse:false?

These seem like related but independent questions. The counter we are adding now would be designed to answer question (2) but could not answer question (1).

Comment by Romans Kasperovics [ 25/Apr/22 ]

To summarise the results of the product triage, for this ticket it is decided to count only the explicit allowDiskUse:false per-query parameters. This new counter will replace the existing counter for allowDiskUse:true from the version 6.0.0.

Comment by David Storch [ 15/Apr/22 ]

Requesting backport to 6.0.

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