io.trino.operator.aggregation.histogram.Histogram 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 io.trino.operator.aggregation.histogram;
import io.trino.spi.block.BlockBuilder;
import io.trino.spi.block.MapBlockBuilder;
import io.trino.spi.block.ValueBlock;
import io.trino.spi.function.AggregationFunction;
import io.trino.spi.function.AggregationState;
import io.trino.spi.function.BlockIndex;
import io.trino.spi.function.BlockPosition;
import io.trino.spi.function.CombineFunction;
import io.trino.spi.function.Description;
import io.trino.spi.function.InputFunction;
import io.trino.spi.function.OutputFunction;
import io.trino.spi.function.SqlType;
import io.trino.spi.function.TypeParameter;
import io.trino.spi.type.Type;
@AggregationFunction("histogram")
@Description("Count the number of times each value occurs")
public final class Histogram
{
private Histogram() {}
@InputFunction
@TypeParameter("T")
public static void input(
@TypeParameter("T") Type type,
@AggregationState("T") HistogramState state,
@BlockPosition @SqlType("T") ValueBlock key,
@BlockIndex int position)
{
state.add(key, position, 1L);
}
@CombineFunction
public static void combine(@AggregationState("T") HistogramState state, @AggregationState("T") HistogramState otherState)
{
state.merge(otherState);
}
@OutputFunction("map(T, BIGINT)")
public static void output(@TypeParameter("T") Type type, @AggregationState("T") HistogramState state, BlockBuilder out)
{
state.writeAll((MapBlockBuilder) out);
}
}