io.trino.operator.IncrementalLoadFactorHashArraySizeSupplier 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;
import it.unimi.dsi.fastutil.HashCommon;
/**
* Hash array size supplier that uses larger load factors for larger arrays
*/
public class IncrementalLoadFactorHashArraySizeSupplier
implements HashArraySizeSupplier
{
// Threshold values provide good performance for smaller hash arrays
// while keeping memory usage limited for larger hash arrays.
// This is tuned based on TPC-DS SF1000.
public static final int THRESHOLD_25 = 1 << 16; // 65536
public static final int THRESHOLD_50 = 1 << 20; // 1048576
private final int multiplier;
public IncrementalLoadFactorHashArraySizeSupplier(int multiplier)
{
this.multiplier = multiplier;
}
@Override
public int getHashArraySize(int expectedCount)
{
if (expectedCount <= THRESHOLD_25 * multiplier) {
return HashCommon.arraySize(expectedCount, 0.25f);
}
if (expectedCount <= THRESHOLD_50 * multiplier) {
return HashCommon.arraySize(expectedCount, 0.50f);
}
return HashCommon.arraySize(expectedCount, 0.75f);
}
}