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Type:
Bug
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Resolution: Won't Do
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: Distributed Query Planning
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None
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Query Optimization
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ALL
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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
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.