/*
* 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.phoenix.iterate;
import static org.apache.phoenix.query.QueryConstants.*;
import java.sql.SQLException;
import org.apache.phoenix.expression.aggregator.Aggregators;
import org.apache.phoenix.schema.tuple.SingleKeyValueTuple;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.util.KeyValueUtil;
public class UngroupedAggregatingResultIterator extends GroupedAggregatingResultIterator {
private boolean hasRows = false;
public UngroupedAggregatingResultIterator( PeekingResultIterator resultIterator, Aggregators aggregators) {
super(resultIterator, aggregators);
}
@Override
public Tuple next() throws SQLException {
Tuple result = super.next();
// Ensure ungrouped aggregregation always returns a row, even if the underlying iterator doesn't.
if (result == null && !hasRows) {
// Generate value using unused ClientAggregators
byte[] value = aggregators.toBytes(aggregators.getAggregators());
result = new SingleKeyValueTuple(
KeyValueUtil.newKeyValue(UNGROUPED_AGG_ROW_KEY,
SINGLE_COLUMN_FAMILY,
SINGLE_COLUMN,
AGG_TIMESTAMP,
value));
}
hasRows = true;
return result;
}
}