[SERVER-55274] mongos aggregate() incorrectly returns empty results before shards are connected Created: 17/Mar/21  Updated: 31/Mar/23  Resolved: 23/Mar/23

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

Type: Bug Priority: Major - P3
Reporter: Ian Boros Assignee: Backlog - Query Optimization
Resolution: Won't Do Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
Assigned Teams:
Query Optimization
Operating System: ALL
Sprint: Query Optimization 2021-04-05, Query Optimization 2021-04-19, Query Optimization 2021-05-03, Query Optimization 2021-05-17, Query Optimization 2021-05-31, Query Optimization 2021-06-14, Query Optimization 2021-06-28, Query Optimization 2021-07-12, Query Optimization 2021-07-26, QO 2021-09-06, Query Optimization 2021-08-09, QO 2021-09-20, QO 2021-10-04, QO 2021-10-18, QO 2021-11-01, QO 2021-11-15, QO 2021-11-29, QO 2021-12-13, QO 2021-12-27, QO 2022-01-10, QO 2022-01-24, QO 2022-02-07, QO 2022-02-21, QO 2022-03-07, QO 2022-03-21, QO 2021-08-23, QO 2022-04-04, QO 2022-04-18, QO 2022-05-02, QO 2022-05-16, QO 2022-05-30, QO 2022-06-13, QO 2022-06-27, QO 2022-07-11
Participants:

 Description   

When getting "routing info" for a sharded query, mongos will return an empty result set if there are no shards connected. See here.

This includes the case where the data is owned by the config servers.

Repro:

 Start CSRS:

./mongod --configsvr --replSet csrs --dbpath ~/data/ --bind_ip localhost --port 20001 

Run rs.initiate()

./mongo --port 20001
> rs.initiate()

Start mongos, connect it to the config server.

./mongos --configdb csrs/localhost:20001 --bind_ip localhost --port 20002

Connect to mongos and run a find() query followed by an equivalent aggregation.

./mongo --port 20002
> use config
> db.mongos.find()
// Returns something
> db.mongos.aggregate([])
// Takes the path linked to earlier. Returns nothing.

 



 Comments   
Comment by Brenda Rodriguez [ 16/Mar/23 ]

kateryna.kamenieva@mongodb.com checking in on this. Any updates?

Comment by Ana Meza [ 15/Jul/22 ]

kateryna.kamenieva@mongodb.com could you please review this one and let us know how would you like to proceed and what is the urgency?

Thanks

Comment by Anton Korshunov [ 11/Jul/22 ]

This ticket has been rolling over QO sprints for ages. Marking for re-triage.

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