/*
* 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.expression.function;
import java.util.List;
import org.apache.hadoop.conf.Configuration;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.aggregator.Aggregator;
import org.apache.phoenix.expression.aggregator.DecimalStddevSampAggregator;
import org.apache.phoenix.expression.aggregator.DistinctValueWithCountClientAggregator;
import org.apache.phoenix.expression.aggregator.DistinctValueWithCountServerAggregator;
import org.apache.phoenix.expression.aggregator.StddevSampAggregator;
import org.apache.phoenix.parse.FunctionParseNode.Argument;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.schema.PDataType;
/**
*
* Built-in function for STDDEV_SAMP(<expression>) aggregate function
*
*
* @since 1.2.1
*/
@BuiltInFunction(name = StddevSampFunction.NAME, args = { @Argument(allowedTypes={PDataType.DECIMAL})})
public class StddevSampFunction extends DistinctValueWithCountAggregateFunction {
public static final String NAME = "STDDEV_SAMP";
public StddevSampFunction() {
}
public StddevSampFunction(List<Expression> childern) {
super(childern);
}
@Override
public Aggregator newServerAggregator(Configuration conf) {
return new DistinctValueWithCountServerAggregator(conf);
}
@Override
public DistinctValueWithCountClientAggregator newClientAggregator() {
if (children.get(0).getDataType() == PDataType.DECIMAL) {
// Special Aggregators for DECIMAL datatype for more precision than double
return new DecimalStddevSampAggregator(children, getAggregatorExpression().getSortOrder());
}
return new StddevSampAggregator(children, getAggregatorExpression().getSortOrder());
}
@Override
public String getName() {
return NAME;
}
@Override
public PDataType getDataType() {
return PDataType.DECIMAL;
}
}