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Type:
Improvement
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Resolution: Works as Designed
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Priority:
Major - P3
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None
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Affects Version/s: 4.0.12
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Component/s: Sharding
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None
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Sharding
It looks like if I have a view on a non-sharded collection, then operations on it (e.g. find, explain) require an extra roundtrip because mongod bounces the first request with an exception that is used by mongos to find out that it's indeed a view:
2019-09-19T09:20:46.883-0500 D TRACKING [replSetDistLockPinger] Cmd: NotSet, TrackingId: 5d838ebe2a67f139ad45d445
2019-09-19T09:20:47.647-0500 D TRACKING [Uptime reporter] Cmd: NotSet, TrackingId: 5d838ebf2a67f139ad45d447
2019-09-19T09:20:48.476-0500 D - [conn5] User Assertion: CommandOnShardedViewNotSupportedOnMongod{ resolvedView: { ns: "test.test", pipeline: [], collation: { locale: "simple" } } }: On sharded systems, resolved views must be executed by mongos src/mongo/db/query/cursor_response.h 165
2019-09-19T09:20:48.479-0500 D TRACKING [conn5] Cmd: find, TrackingId: 5d838ec02a67f139ad45d44c
2019-09-19T09:20:48.483-0500 I COMMAND [conn5] command test.view appName: "MongoDB Shell" command: find { find: "view", filter: { x: 3.0 }, lsid: { id: UUID("a9e2ff0d-2a78-4a7a-b8d5-16f14ac83375") }, $clusterTime: { clusterTime: Timestamp(1568902782, 1), signature: { hash: BinData(0, 0000000000000000000000000000000000000000
I think this is not necessary for non-sharded collections.