All Products
Search

This Product

    DataWorks:Scenario: Effects of DST transitions on node execution

    Document Center

    DataWorks:Scenario: Effects of DST transitions on node execution

    Last Updated:Jul 18, 2026

    When daylight saving time (DST) starts or ends, instance generation and scheduled times for nodes in DST-observing regions are affected. This topic describes how DataWorks handles these transitions.

    Background information

    DataWorks ensures that nodes run correctly on DST transition days. The following example uses an hourly node in a DST-observing region to illustrate the handling logic:
    • When DST starts (spring forward):进入夏令时
      • Number of instances: DST starts at 02:00, when the clock moves forward one hour from 02:00 to 03:00. Because the 2:00 AM hour is skipped, DataWorks does not generate an instance for this hour, so an hourly node produces only 23 instances on this day.
      • Instance scheduled time: The time shift when DST starts causes the scheduled run time of some nodes to change. For example, the scheduled time for the fourth instance of an hourly node, which would normally be 04:00, changes to 05:00.
      Important
      • For daily, weekly, or monthly nodes, if the scheduled run time falls within the skipped time window on the day DST starts, the node does not run. Instead, its instance is set to dry-run.
      • On this day, subtracting 10 minutes from 03:00 results in 01:50.
    • When DST ends (fall back):退出夏令时
      Number of instances: An hourly node produces 24 instances. Although the system generates two instances scheduled for 02:00, it only keeps the instance for the second occurrence of 02:00.
      Important Due to the repeated hour, subtracting 10 minutes from the second 02:00 results in 02:50.

    Limitations

    Daylight saving time transitions affect only nodes in regions where DST is observed.

    Impacts when DST starts

    Impact 1: Instance generation

    • Scenario 1: Impact on hourly and minute-based nodes
      For example, if an hourly node is configured with the scheduling cycle described below, DataWorks generates one instance per hour, for a total of 24 instances on a typical day. On the day DST starts, only 23 instances are generated because the instance for 02:00 is skipped.
      Note DST starts at 02:00. The clock moves forward one hour from 02:00 to 03:00, so no instance is generated at 02:00.
      Example parameters: instance generation mode is set to Generate on the next day (T+1), scheduling type is auto triggered, scheduling time zone is America/New_York, the scheduling cycle is Hour with a start time of 00:00, an end time of 23:59, and an interval of 1 hour.
    • Scenario 2: Impact on daily nodes
      DataWorks still generates one instance for a daily node on the day DST starts, but whether the node runs normally depends on its scheduled time.
      • If the scheduled time of the node falls within the 02:00–03:00 window, the instance is set to Dry Run.
      • If the scheduled time is outside the 02:00–03:00 window, the node runs normally.
      Example configuration: if you set the scheduling cycle to Day and the scheduled time to 02:00, the corresponding cron expression is 00 00 02 * * ?.

    Impact 2: Parameter substitution

    • Scenario 1: If a node is scheduled for 03:00 and uses the scheduling parameter $[hh24-1/24], the parameter normally resolves to 02:00. When DST starts, it resolves to 01:00.
    • Scenario 2: If a node is scheduled for 02:00 and uses the scheduling parameter $[hh24-1/24], the parameter normally resolves to 01:00. When DST starts, it still resolves to 01:00. If this is a daily node, the instance is set to Dry Run.

    Impacts when DST ends

    Impact 1: Instance generation

    For an hourly node, the day DST ends is 25 hours long and includes two occurrences of the 02:00 hour. However, DataWorks generates only 24 instances for the node because it keeps only the instance for the second occurrence of 02:00.

    Impact 2: Parameter substitution

    If a node uses scheduling parameters calculated from the instance's scheduled time, the 25-hour day can cause values to differ from a normal day. Specific scenarios:
    • Scenario 1: If a node is scheduled for 03:00 and uses the scheduling parameter $[hh24-2/24], the parameter normally resolves to 01:00. When DST ends, it resolves to 02:00.
    • Scenario 2: If a node is scheduled for 02:00 and uses the scheduling parameter $[hh24-1/24], the parameter normally resolves to 01:00. When DST ends, it resolves to 02:00.