Package org.apache.flink.table.runtime.operators.window.tvf.slicing

Interface SliceSharedAssigner

All Superinterfaces:
Serializable, SliceAssigner, WindowAssigner
All Known Implementing Classes:
SliceAssigners.CumulativeSliceAssigner, SliceAssigners.HoppingSliceAssigner, SliceAssigners.SlicedSharedSliceAssigner
@Internal public interface SliceSharedAssigner extends SliceAssigner
A SliceAssigner which shares slices for windows, which means a window is divided into multiple slices and need to merge the slices into windows when emitting windows.

Classical window of SliceSharedAssigner is hopping window.

  • Method Details

    • mergeSlices

      void mergeSlices(long sliceEnd, MergeCallback<Long,Iterable<Long>> callback) throws Exception
      Determines which slices (if any) should be merged and then merge them.
      Parameters:
      sliceEnd - the triggered slice, identified by end timestamp
      callback - a callback that can be invoked to signal which slices should be merged.
      Throws:
      Exception

    • asyncMergeSlices

      org.apache.flink.api.common.state.v2.StateFuture<org.apache.flink.api.java.tuple.Tuple2<org.apache.flink.table.data.RowData,org.apache.flink.table.data.RowData>> asyncMergeSlices(long sliceEnd, AsyncMergeCallback<Long,Iterable<Long>> callback) throws Exception
      Determines which slices (if any) should be merged and then merge them.
      Parameters:
      sliceEnd - the triggered slice, identified by end timestamp
      callback - a callback that can be invoked to signal which slices should be merged.
      Returns:
      f0 is the accumulators after merging, f1 is the result of the aggregation from the merged accumulators with this slice end as namespace
      Throws:
      Exception

    • nextTriggerWindow

      Optional<Long> nextTriggerWindow(long windowEnd, Supplier<Boolean> isWindowEmpty)
      Returns the optional end timestamp of next window which should be triggered. Empty if no following window to trigger for now.

      The purpose of this method is avoid register too many timers for each hopping and cumulative slice, e.g. HOP(1day, 10s) needs register 8640 timers for every slice. In order to improve this, we only register one timer for the next window. For hopping windows we don't register next window if current window is empty (i.e. no records in current window). That means we will have one more unnecessary window triggered for hopping windows if no elements arrives for a key for a long time. We will skip to emit window result for the triggered empty window, see AsyncStateSliceSharedWindowAggProcessor#fireWindow(Long, Long).

      Parameters:
      windowEnd - the current triggered window, identified by end timestamp
      isWindowEmpty - a supplier that can be invoked to get whether the triggered window is empty (i.e. no records in the window).

    • nextTriggerWindow

      Optional<Long> nextTriggerWindow(long windowEnd, org.apache.flink.table.data.RowData acc, Function<org.apache.flink.table.data.RowData,Boolean> isWindowEmpty)