[SERVER-43357] FTDC ops writes not reflecting aggregation $out Created: 14/Sep/19  Updated: 27/Oct/23  Resolved: 16/Jan/20

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

Type: Bug Priority: Minor - P4
Reporter: Josef Ahmad Assignee: Ted Tuckman
Resolution: Works as Designed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: PNG File ftdc.png    
Sprint: Query 2019-10-21, Query 2019-11-04, Query 2019-11-18, Query 2019-12-02, Query 2019-12-16, Query 2019-12-30, Query 2020-01-13, Query 2020-01-27
Participants:
Case:

 Description   

2019-09-14T10:39:37.778+0000 command: aggregate
pipeline: [ { $group: { _id: "$_id" } }, { $out: "cout" } ]
COLLSCAN keysExamined:0 docsExamined:1000 cursorExhausted:1 

 

Is this intended behaviour?



 Comments   
Comment by Ted Tuckman [ 07/Jan/20 ]

So looking at what is happening here, it seems that the "ss ops" row in t2 is pulling data from the opLatencies document in serverStatus. That document is updated here in the code, and so only gets updated for operations that enter the server through the service entry point. The opcounter is updated here and so works for all writes (in the insert case). With the names in serverStatus, this makes sense to me – $out writes don't contribute to insert latencies as the requests are not coming over the network.

Given this, my instinct is either to do nothing or change the name in t2 to reflect that that row comes from the opLatencies category. asya, kateryna.kamenieva does that seem reasonable? josef.ahmad would that clear up the confusion?

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