• Vedran Kesegic (1/13/2013)


    But, it turns out that checkpoint indeed occurs even at the beginning of a log backup, not just full/diff backup.

    It can occur. It's not an automatic thing that always happens, but it can (I've seen checkpoints triggered by a log backup when either traceflags or server settings have resulted in a lack of automatic checkpoints).

    But the checkpoint (better to say: the lack of it) can prevent VLF to be cleared (when clearing process is triggered by log backup).

    Of course it can.

    What I'm saying, and have been saying, is that a checkpoint after a log backup will not mark additional log records as reusable and hence will not allow a shrink to reclaim more space than it would if the checkpoint had not been run after the log backup.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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