Package org.apache.flink.table.runtime.operators.over.frame

Interface OverWindowFrame

All Superinterfaces:

Serializable

All Known Implementing Classes:

InsensitiveOverFrame, OffsetOverFrame, RangeSlidingOverFrame, RangeUnboundedFollowingOverFrame, RangeUnboundedPrecedingOverFrame, RowSlidingOverFrame, RowUnboundedFollowingOverFrame, RowUnboundedPrecedingOverFrame, SlidingOverFrame, UnboundedFollowingOverFrame, UnboundedOverWindowFrame, UnboundedPrecedingOverFrame

public interface OverWindowFrame
extends Serializable

A window frame calculates the results for those records belong to a window frame. Before use a frame must be prepared by passing it all the records in the current partition. A frame is a subset of the current partition and the frame clause specifies how to define the subset. Frames are determined with respect to the current row, which enables a frame to move within a partition depending on the location of the current row within its partition. More information: https://docs.oracle.com/cd/E17952_01/mysql-8.0-en/window-functions-frames.html

E.g.: SELECT d, e, f, sum(e) over (partition by d order by e rows between 5 PRECEDING and 2 FOLLOWING), -- frame 1 count(*) over (partition by d order by e desc rows between 6 PRECEDING and 2 FOLLOWING), -- frame 2 max(f) over (partition by d order by e rows between UNBOUNDED PRECEDING and CURRENT ROW), -- frame 3 min(h) over (partition by d order by e desc rows between CURRENT ROW and UNBOUNDED FOLLOWING), -- frame 4 h FROM Table5 The above sql has 4 frames.

Over AGG means that every Row has a corresponding output. OverWindowFrame is called by: 1.Get all data and invoke prepare(ResettableExternalBuffer) for partition 2.Then each Row is traversed one by one to invoke process(int, RowData) to get the calculation results of the currentRow.

Method Summary

Modifier and Type	Method	Description
static org.apache.flink.table.data.binary.BinaryRowData	getNextOrNull(ResettableExternalBuffer.BufferIterator iterator)	Get next row from iterator.
void	open(ExecutionContext ctx)	Open to init with ExecutionContext.
void	prepare(ResettableExternalBuffer rows)	Prepare for next partition.
org.apache.flink.table.data.RowData	process(int index, org.apache.flink.table.data.RowData current)	return the ACC of the window frame.

Method Detail

open

void open(ExecutionContext ctx)
   throws Exception

Open to init with ExecutionContext.

Throws:

Exception

prepare

void prepare(ResettableExternalBuffer rows)
      throws Exception

Prepare for next partition.

Throws:

Exception

process

org.apache.flink.table.data.RowData process(int index,
                                            org.apache.flink.table.data.RowData current)
                                     throws Exception

return the ACC of the window frame.

Throws:

Exception

getNextOrNull

static org.apache.flink.table.data.binary.BinaryRowData getNextOrNull(ResettableExternalBuffer.BufferIterator iterator)

Get next row from iterator. Return null if iterator has no next. TODO Maybe copy is repeated.