Package org.apache.flink.streaming.api.windowing.assigners

Class SlidingEventTimeWindows

  • All Implemented Interfaces:
    Serializable
    @PublicEvolving
public class SlidingEventTimeWindows
extends WindowAssigner<Object,​TimeWindow>
    A WindowAssigner that windows elements into sliding windows based on the timestamp of the elements. Windows can possibly overlap.

    For example, in order to window into windows of 1 minute, every 10 seconds: 

    
 DataStream<Tuple2<String, Integer>> in = ...;
 KeyedStream<Tuple2<String, Integer>, String> keyed = in.keyBy(...);
 WindowedStream<Tuple2<String, Integer>, String, TimeWindow> windowed =
   keyed.window(SlidingEventTimeWindows.of(Duration.ofMinutes(1), Duration.ofSeconds(10)));
    See Also:
    Serialized Form

    • Constructor Detail

      • SlidingEventTimeWindows

        protected SlidingEventTimeWindows​(long size,
                                  long slide,
                                  long offset)

    • Method Detail

      • getSize

        public long getSize()

      • getSlide

        public long getSlide()

      • getDefaultTrigger

        public Trigger<Object,​TimeWindow> getDefaultTrigger()
        Description copied from class: WindowAssigner
        Returns the default trigger associated with this WindowAssigner.

        1. If you override getDefaultTrigger(), the getDefaultTrigger() will be invoked and the getDefaultTrigger(StreamExecutionEnvironment env) won't be invoked. 2. If you don't override getDefaultTrigger(), the getDefaultTrigger(StreamExecutionEnvironment env) will be invoked in the default implementation of the getDefaultTrigger().

        Specified by:
        getDefaultTrigger in class WindowAssigner<Object,​TimeWindow>

      • of

        public static SlidingEventTimeWindows of​(Duration size,
                                         Duration slide)
        Creates a new SlidingEventTimeWindows WindowAssigner that assigns elements to sliding time windows based on the element timestamp.
        Parameters:
        size - The size of the generated windows.
        slide - The slide interval of the generated windows.
        Returns:
        The time policy.

      • of

        public static SlidingEventTimeWindows of​(Duration size,
                                         Duration slide,
                                         Duration offset)
        Creates a new SlidingEventTimeWindows WindowAssigner that assigns elements to time windows based on the element timestamp and offset.

        For example, if you want window a stream by hour,but window begins at the 15th minutes of each hour, you can use of(Duration.ofHours(1), Duration.ofMinutes(15)), then you will get time windows start at 0:15:00,1:15:00,2:15:00,etc.

        Rather than that,if you are living in somewhere which is not using UTC±00:00 time, such as China which is using UTC+08:00,and you want a time window with size of one day, and window begins at every 00:00:00 of local time,you may use of(Duration.ofDays(1), Duration.ofHours(-8)). The parameter of offset is Duration.ofHours(-8)) since UTC+08:00 is 8 hours earlier than UTC time.

        Parameters:
        size - The size of the generated windows.
        slide - The slide interval of the generated windows.
        offset - The offset which window start would be shifted by.
        Returns:
        The time policy.

      • getWindowSerializer

        public org.apache.flink.api.common.typeutils.TypeSerializer<TimeWindow> getWindowSerializer​(org.apache.flink.api.common.ExecutionConfig executionConfig)
        Description copied from class: WindowAssigner
        Returns a TypeSerializer for serializing windows that are assigned by this WindowAssigner.
        Specified by:
        getWindowSerializer in class WindowAssigner<Object,​TimeWindow>