com.facebook.presto.spi.function

Interface WindowFunction

All Known Implementing Classes:

RankingWindowFunction, ValueWindowFunction

public interface WindowFunction

Method Summary

Modifier and Type	Method and Description
void	processRow(BlockBuilder output, int peerGroupStart, int peerGroupEnd, int frameStart, int frameEnd) Process a row by outputting the result of the window function.
void	reset(WindowIndex windowIndex) Reset state for a new partition (including the first one).

Method Detail

reset

void reset(WindowIndex windowIndex)

Reset state for a new partition (including the first one).

Parameters:

windowIndex - the window index which contains sorted values for the partition

processRow

void processRow(BlockBuilder output,
                int peerGroupStart,
                int peerGroupEnd,
                int frameStart,
                int frameEnd)

Process a row by outputting the result of the window function.

This method provides information about the ordering peer group. A peer group is all of the rows that are peers within the specified ordering. Rows are peers if they compare equal to each other using the specified ordering expression. The ordering of rows within a peer group is undefined (otherwise they would not be peers).

Parameters:

output - the BlockBuilder to use for writing the output row

peerGroupStart - the position of the first row in the peer group

peerGroupEnd - the position of the last row in the peer group

frameStart - the position of the first row in the window frame

frameEnd - the position of the last row in the window frame