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  1. Core Server
  2. SERVER-51333

setFeatureCompatibilityVersion should fail when downgrading from FCV 4.4 to FCV 4.2 with long collection names present

    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 4.4.3
    • Affects Version/s: None
    • Component/s: Catalog, Replication
    • Labels:
    • Minor Change
    • ALL
    • Execution Team 2020-11-02, Execution Team 2020-12-14, Execution Team 2020-12-28
    • 38

      DatabaseImpl::_checkCanCreateCollection() throws an exception if a collection with a name longer than 120 characters is attempted to be created while in FCV 4.2. However, a node undergoing initial sync will also call that function and (depending on whether the admin.system.version collection has already been cloned) would fail its initial sync attempt and eventually exhaust its retries.

      [js_test:repro_initial_sync_long_collection_name] 2020-10-02T18:19:19.708+0000 d20021| {"t":{"$date":"2020-10-02T18:19:19.708+00:00"},"s":"E",  "c":"REPL",     "id":21416,   "ctx":"ReplCoordExtern-0","msg":"Initial sync failed, shutting down now. Restart the server to attempt a new initial sync"}
      [js_test:repro_initial_sync_long_collection_name] 2020-10-02T18:19:19.708+0000 d20021| {"t":{"$date":"2020-10-02T18:19:19.708+00:00"},"s":"F",  "c":"-",        "id":23095,   "ctx":"ReplCoordExtern-0","msg":"Fatal assertion","attr":{"msgid":40088,"error":"InitialSyncFailure: error cloning databases :: caused by :: IncompatibleServerVersion: Error cloning collection 'test.long_collection_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' :: caused by :: Fully qualified namespace is too long for FCV 4.2. Upgrade to FCV 4.4 to create this namespace. Namespace: test.long_collection_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx FCV 4.2 Limit: 120","file":"src/mongo/db/repl/replication_coordinator_impl.cpp","line":754}}

            gregory.wlodarek@mongodb.com Gregory Wlodarek
            max.hirschhorn@mongodb.com Max Hirschhorn
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