/**
* Copyright (C) 2014-2016 LinkedIn Corp. (pinot-core@linkedin.com)
*
* 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.linkedin.pinot.core.query.aggregation.groupby;
import com.linkedin.pinot.core.query.aggregation.function.AggregationFunction;
import java.util.Iterator;
/**
* This class holds the result of aggregation group by queries.
* It provides an iterator over group-by keys, and provides a method
* to get the aggregation result for the given group-by key.
*/
public class AggregationGroupByResult {
private final GroupKeyGenerator _groupKeyGenerator;
private final AggregationFunction[] _aggregationFunctions;
private final GroupByResultHolder[] _resultHolders;
public AggregationGroupByResult(GroupKeyGenerator groupKeyGenerator, AggregationFunction[] aggregationFunctions,
GroupByResultHolder[] resultHolders) {
_groupKeyGenerator = groupKeyGenerator;
_aggregationFunctions = aggregationFunctions;
_resultHolders = resultHolders;
}
/**
* Returns an iterator for group-by keys.
* @return
*/
public Iterator<GroupKeyGenerator.GroupKey> getGroupKeyIterator() {
return _groupKeyGenerator.getUniqueGroupKeys();
}
/**
*
* Given a group-by key and an index into the result holder array, returns
* the corresponding aggregation result.
*
* Clients are expected to order the resultHolder array in the same order in which
* the aggregation functions appear in the brokerRequest. This way they can simply
* pass the index of aggregation function and get the result. This is purely a
* runtime optimization, so that:
* - Same groupKey can be re-used for multiple aggregation functions.
* - Avoid any name based association (and lookup) between aggregation function
* and its result in this class.
*
* @param groupKey
* @param index
* @return
*/
public Object getResultForKey(GroupKeyGenerator.GroupKey groupKey, int index) {
return _aggregationFunctions[index].extractGroupByResult(_resultHolders[index], groupKey.getFirst());
}
}