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  1. Core Server
  2. SERVER-47425

When 4.2 discovers log version 4 records on startup, continue to write log version 4 records

    • Type: Icon: Improvement Improvement
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 4.2.6, 4.4.0-rc2
    • Affects Version/s: 4.2.6, 4.4.0
    • Component/s: Storage
    • Labels:
    • Fully Compatible
    • Execution Team 2020-04-20

      Downgrading from 4.4 -> 4.2.6 -> 4.2.x (x < 6) is not allowed. The current state of 4.2.6 will always write out log version 3 which earlier 4.2 versions understand. However, earlier 4.2 versions will fail to startup on the checkpointed data files in a messy way (likely a seg fault)

      Instead, 4.2.6 could discover if it's reading log version 4 records at startup (which is only possible via a 4.4 downgrade) and choose to write out log version 4 records. This would result in earlier versions failing with an "incompatible log version" error.

            daniel.gottlieb@mongodb.com Daniel Gottlieb (Inactive)
            daniel.gottlieb@mongodb.com Daniel Gottlieb (Inactive)
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