io.trino.operator.scalar.HyperLogLogFunctions 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.scalar;
import io.airlift.slice.Slice;
import io.airlift.stats.cardinality.HyperLogLog;
import io.trino.operator.aggregation.ApproximateSetAggregation;
import io.trino.spi.function.Description;
import io.trino.spi.function.ScalarFunction;
import io.trino.spi.function.SqlType;
import io.trino.spi.type.StandardTypes;
public final class HyperLogLogFunctions
{
private HyperLogLogFunctions() {}
@ScalarFunction
@Description("Compute the cardinality of a HyperLogLog instance")
@SqlType(StandardTypes.BIGINT)
public static long cardinality(@SqlType(StandardTypes.HYPER_LOG_LOG) Slice serializedHll)
{
return HyperLogLog.newInstance(serializedHll).cardinality();
}
@ScalarFunction
@Description("An empty HyperLogLog instance")
@SqlType(StandardTypes.HYPER_LOG_LOG)
public static Slice emptyApproxSet()
{
return ApproximateSetAggregation.newHyperLogLog().serialize();
}
}