In the current implementation, a checkpoint only occurs when the NameNode starts up. Work is in progress to support periodic checkpointing in the near future.

在当前实现中，checkpoint只发生在Namenode启动时，在不久的将来我们将实现支持周期性的checkpoint。

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Only those images that correspond to a consistent snapshot are written to the checkpoint file, and the row shadows allow the currently executing transactions to run unrestricted during checkpointing.

只有那些与一致性快照相符的镜像被写到检查点文件，行影子使当前执行的事务可以在检查点创建期间不受限制地运行。

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On the seventh day of the race, Buser was first out of the checkpoint at Eagle Island, where a single cabin is the only dwelling in the otherwise uninhabited stretch of trail.

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