Apache spark spark结构化流媒体检查点目录下的子目录

spark结构化流的检查点目录创建四个子目录。它们都是干什么用的

/warehouse/test_topic/checkpointdir1/commits
/warehouse/test_topic/checkpointdir1/metadata
/warehouse/test_topic/checkpointdir1/offsets
/warehouse/test_topic/checkpointdir1/sources

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从StreamExecution类文档：

/**
   * A write-ahead-log that records the offsets that are present in each batch. In order to ensure
   * that a given batch will always consist of the same data, we write to this log *before* any
   * processing is done.  Thus, the Nth record in this log indicated data that is currently being
   * processed and the N-1th entry indicates which offsets have been durably committed to the sink.
   */
  val offsetLog = new OffsetSeqLog(sparkSession, checkpointFile("offsets"))

  /**
   * A log that records the batch ids that have completed. This is used to check if a batch was
   * fully processed, and its output was committed to the sink, hence no need to process it again.
   * This is used (for instance) during restart, to help identify which batch to run next.
   */
  val commitLog = new CommitLog(sparkSession, checkpointFile("commits"))

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元数据日志用于获取与查询相关的信息。e、 g在KafkaSource中，它用于写入查询的起始偏移量（每个分区的偏移量）

还需要一些源文件夹的清晰信息。我知道这篇文章太旧了，但是有人在这篇文章上活跃吗。请解释一下。谢谢，根据上面的解释，“元数据”存储查询的起始偏移量，但当我检查我的文件夹时，它的内容像“{”id:“3b7f07a0-2256-4097-83d4-dfeab6cf56cd”}”。我不知道这个十六进制代表什么。你能用例子解释一下吗。