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  1. Core Server
  2. SERVER-22572

readConcern majority doesn't consider replica-set changes

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    • Icon: Bug Bug
    • Resolution: Duplicate
    • Icon: Major - P3 Major - P3
    • None
    • 3.2.1
    • Replication
    • None
    • ALL
    • Repl 11 (03/11/16), Repl 12 (04/01/16)

    Description

      It would appear the only reason to throw away the set of snapshots used for readConcern is if the local node enters ROLLBACK:
      https://github.com/mongodb/mongo/blob/f8dadcefeef7e738d7063ae2df57b9c856b402da/src/mongo/db/repl/replication_coordinator_impl.cpp#L2518

      Replica-set reconfigs would seem to be another way to change the conditions needed to fulfill readConcern majority. For example, in a 5-member replica-set where 2 members are non-voting requires only 2 of the voting members to fulfill a majority readConcern. Reconfig to allow the other 2 members to vote means the set should now demand 3 members to achieve readConcern majority. However, the existing 'verified' snapshot on all members would continue to be used for this purpose despite it (not necessarily) fulfilling the current requirements.

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            scotthernandez Scott Hernandez (Inactive)
            andrew.ryder@mongodb.com Andrew Ryder (Inactive)
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              Created:
              Updated:
              Resolved: