com.facebook.presto.jdbc.internal.spi.function.WindowFunction Maven / Gradle / Ivy
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.jdbc.internal.spi.function;
import com.facebook.presto.jdbc.internal.spi.block.BlockBuilder;
public interface WindowFunction
{
/**
* Reset state for a new partition (including the first one).
*
* @param windowIndex the window index which contains sorted values for the partition
*/
void reset(WindowIndex windowIndex);
/**
* 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).
*
* @param output the {@link BlockBuilder} to use for writing the output row
* @param peerGroupStart the position of the first row in the peer group
* @param peerGroupEnd the position of the last row in the peer group
* @param frameStart the position of the first row in the window frame
* @param frameEnd the position of the last row in the window frame
*/
void processRow(BlockBuilder output, int peerGroupStart, int peerGroupEnd, int frameStart, int frameEnd);
}