org.apache.hadoop.hive.ql.stats.estimator.PessimisticStatCombiner Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.hive.ql.stats.estimator;
import java.util.Optional;
import org.apache.hadoop.hive.ql.plan.ColStatistics;
/**
* Combines {@link ColStatistics} objects to provide the most pessimistic estimate.
*/
public class PessimisticStatCombiner {
private boolean inited;
private ColStatistics result;
public void add(ColStatistics stat) {
if (!inited) {
inited = true;
result = stat.clone();
result.setRange(null);
result.setIsEstimated(true);
return;
} else {
if (stat.getAvgColLen() > result.getAvgColLen()) {
result.setAvgColLen(stat.getAvgColLen());
}
if (stat.getCountDistint() > result.getCountDistint()) {
result.setCountDistint(stat.getCountDistint());
}
if (stat.getNumNulls() > result.getNumNulls()) {
result.setNumNulls(stat.getNumNulls());
}
if (stat.getNumTrues() > result.getNumTrues()) {
result.setNumTrues(stat.getNumTrues());
}
if (stat.getNumFalses() > result.getNumFalses()) {
result.setNumFalses(stat.getNumFalses());
}
if (stat.isFilteredColumn()) {
result.setFilterColumn();
}
}
}
public Optional getResult() {
return Optional.of(result);
}
}