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  1. Core Server
  2. SERVER-33932

Confirm storage engine support for point-in-time reads in waitForReadConcern()

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    • Icon: Bug Bug
    • Resolution: Duplicate
    • Icon: Major - P3 Major - P3
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    Description

      Both readConcern level majority and snapshot require a storage engine that supports snapshot isolation. It is possible to bypass this check when:

      1. Running a sharded cluster with standalone shards
      2. Executing a readConcern level majority read operation with afterClusterTime

      In this case, we skip calling replCoord->waitUntilOpTimeForRead() here and won't then call ReplicationCoordinatorImpl::_validateReadConcern() which will perform validation.

      A proposal to fix would be to add the "if majority then isReadCommittedSupportedByStorageEngine()" check to waitForReadConcern() as a more universal check. We could then change the ReplicationCoordinatorImpl::_validateReadConcern() validation to be an invariant.

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            backlog-server-execution Backlog - Storage Execution Team
            james.wahlin@mongodb.com James Wahlin
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